There are a few that I like to use and I'm curious if they are allowed: zoom (I use WI Zoom), essential mod, apple skin, xaero's minimap/world map, and iris shaders (I use complimentary unbound). Also I have heard some launchers aren't allowed, I use ATLauncher (not to be confused with TLauncher).
No none of those are allowed. You can read the rules here on the leaderboard page which includes allowed mods etc. Prism, MultiMc and the default launcher are allowed.
This vid shows how to setup 1.16 rsg (most popular category)
The rules for the Minecraft: Java Edition leaderboards have officially been rewritten and updated. The goal of rewriting the rules was to create one, definitive place wherein all MCSR rules are stored, completely eliminating any a
