Maximize/"Harden" Firefox privacy settings
(via Mental Outlaw YT channel and Chris Xiao's Yet Another Firefox Hardening
article and Unix Sheikh's Choose your Browser Carefully article):

Install Ublock Origin
Install UBlacklist
Install LibRedirect
Install NoScript
Install Chameleon
Install LocalCDN
Install OneTab (set OneTab to not open up on startup)
Install DarkReader (in DarkReader menu under More, set to Static)
Install Vimium-FF
Set Default Search Engine to Duck Duck Go Lite
Install Always active Window - Always Visible
Install Classic mode for Wikipedia
Install Stack Overflow Prettifier
Install ClearURLs
Install Cookie AutoDelete
Install Don't Track Me Google
Install Measure-it
Install FastForward
Install Firefox Translations
Install User-Agent-Switcher and Manager
Install OverbiteWX
Install Return YouTube Dislike
Install SponsorBlock for Youtube-Skip Sponsorships (under Misc, enable invidious 3rd party)
Insall Vue.js devtools
Install WAVE Evaluation Tool
Install Wappalyzer
Install Manjaro Theme (matcha-dark-azul for blue, matcha-dark-sea for green)
Get Firefox to remember nothing through Preferences setting
Set Firefox to never visit non  https websites
Disable smooth scrolling

about:config settings
(Optional): Turn off Javascript
media.peerconnection.enabled set to false #breaks real-time audio/video
media.navigator.enabled to false #breaks real-time audio/video
media.gmp
devtools.onboarding.telemetry.logged to false
datareporting.policy.dataSubmissionEnabled set to false
app.normandy.enabled set to false
extensions.pocket.enabled to false
extensions.formautofill.available set to blank
extensions.screenshots.disabled set to true
extensions.webcompat-reporter.enabled set to false
privacy.resistfingerprinting set to true #noticeable performance and stability impact, proceed with caution.
privacy.firstparty.isolate to true
network.dns.disablePrefetch to true
network.predictor.enabled set to false
network.prefetch-next to false
network.http.sendRefererHeader to 0 #sites with forms and logins may break
network.http.referer.XoriginPolicy to 1
network.cookie.lifetimePolicy to 2
network.trr.mode to 3
pdfjs.enableScripting to false
identity.fxaccounts.enabled to false
geo.enabled to false
dom.webnotifications.enabled to false
security.ssl3.rsa_des_ede3_sha set to false
security.ssl.require_safe_negotiation set to true
security.tls.version set to at least 3 (4 highest setting as of 2021, but not necessary according to Mental Outlaw)
security.tls.enable_Ortt_data set to false
browser.shell.checkDefaultBrowser = false
browser.formfill.enable set to false
browser.cache.disk.enable set to false
browser.cache.disk_cache_ssl set to false
browser.cache.memory.enable set to false
browser.cache.offline.enable set to false
browser.cache.insecure.enable set to false
browser.privatebrowsing.autostart set to true
browser.urlbar.speculativeConnect.enabled set to false
browser.urlbar.maxRichResults set to 0
browser.search.suggest.enabled set to false
plugin.scan.plid.all set to false (same, couldn't find)
browser.ping-centre.telemetry set to false
browser.newtabpage.activity-stream.feeds.telemetry set to false
browser.newtabpage.activity-stream.telemetry set to false
browser.newtabpage.activity-stream.section.highlights.includePocket to false
browser.tabs.crashReporting.sendReport to false
browser.tabs.tabmanager.enabled to false
browser.tabs.cardPreview.enabled to false
browser.tabs.cardPreview.showThumbnails to false
browser.uidensity to 1 (makes the browser's tabs not so huge for firefox 89+)
browser.chrome.site_icons to false (removes favicons)
browser.tabs.tabsmanager.enabled to false
accessibility.force_disabled to 1 (improves performance)
extensions.unifiedExtensions.enabled to false (to remove item visually, remove all extensions from list)
devtools.onboarding.telemetry.logged to false
toolkit.telemetry.enabled to false
toolkit.telemetry.server Delete the URL and leave it empty
toolkit.telemetry.archive.enabled set to false
toolkit.telemetry.bhrPing.enabled set to false
toolkit.telemetry.firstShutdownPing.enabled set to false
toolkit.telemetry.newProfilePing.enabled set to false
toolkit.telemetry.unified set to false
toolkit.telemetry.updatePing.enabled set to false
toolkit.telemetry.shutdownPingSender.enabled set to false
webgl.disabled set to true
privacy.firstparty.isolate set to true
security.ssl.enable_false_start set to false
browser.sessionstore.resume_from_crash to false

go into ublock origin and check the 'Prevent WebRTC from leaking local IP addresses' box.
go into usr/lib/firefox/distribution and open/create package.json and input the following:

{
  "policies": {
    "DisableAppUpdate": true,
    "DisableFirefoxAccounts": true,
    "DisableTelemetry": true,
    "DNSOverHTTPS": {
      "Enabled": false,
      "Locked": true
    },
    "DontCheckDefaultBrowser": true,
    "NetworkPrediction": false,
    "PromptForDownloadLocation": true,
    "SearchEngines": {
      "PreventInstalls": true
    },
    "SearchSuggestEnabled": false,
    "NetworkPrediction": false
  }
}

The following isn't privacy related, but turns off proton in firefox, which makes better use of screenspace:

browser.proton.enabled set to false
browser.proton.modals.enabled set to false
browser.proton.doorhangers.enabled set to false
browser.proton.contextmenus.enabled set to false
browser.sessionstore.resume_from_crash false

Copy the chrome directory into the profile ($HOME/.librewolf/*.default-release)
This feature isn't officially supported anymore so enable it by heading to
about:config and find/set:
toolkit.legacyUserProfileCustomizations.stylesheets : true (enables userChrome)

Custom Caret Widths for Text Cursor:
In about:config, add these new custom properties (they don't exist by default):
ui.caretWidth (set to number, and set to 10)
ui.caretBlinkTime (set to number, and set to 0 to disable blink)

Disable "This Time Search With":
browser.urlbar.scotchBonnet.enableOverride to false


browser.urlbar.maxRichResults to 0 (removes annoying blue search suggestions)
Go into Ublock Origin, Under Filter List, open Annoyances and click all
checkboxes (blocks annoying cookie confirmation popups amongst others).

Disable JavaScript JIT Compiler:
javascript.options.baselinejit false
javascript.options.ion false
javascript.options.wasm false
javascript.options.asmjs false

In about:preferences#privacy:

Enable secure DNS using Default protection.
Use custom secure DNS, under Max Protection, input mullvad's DNS server:
https://base.dns.mullvad.net/dns-query

Disable Ads
browser.shopping.experience2023.active to false
browser.shopping.experience2023.ads.userEnabled to false
browser.shopping.experience2023.autoOpen.userEnabled to false
browser.shopping.experience2023.showKeepSidebarClosedMessage to false
browser.shopping.experience2023.suvey.enabled to false

In Ublock Origin:
Enable all filter lists in settings/filter lists
Add bypass filter list:
https://gitflic.ru/project/magnolia1234/bypass-paywalls-clean-filters/blob/raw?file=bpc-paywall-filter.txt
Add huge ai black list filter list
https://raw.githubusercontent.com/laylavish/uBlockOrigin-HUGE-AI-Blocklist/main/list_uBlacklist.txt

In UBlacklist, do the same for the huge ai blacklist, under options/subscriptions, click "Add a subscriptions", and place the filter list in the form:
https://raw.githubusercontent.com/laylavish/uBlockOrigin-HUGE-AI-Blocklist/main/list_uBlacklist.txt

For Android Only (Ironfox/Fennec):
about:config:

network.trr.mode to 0

(defaults to OS level DNS resolver, set in Android Network settings, Private DNS field, to https://base.dns.mullvad.net/dns-query)

Set zoom to only be specific to tab you are on:
browser.zoom.siteSpecific to false