Recommended Client-side mods for 1.16.5
Make sure you are selecting the right version on each page!
Optifine (Better performance, shaders, and optifine resourcepack support.)
https://optifine.net/downloadx?f=OptiFine_1.16.5_HD_U_G8.jar&x=224d1346f3c177519773c3bd3e5fdc81
FreshAnimations + Addon(Requires optifine; adds life to mobs with cool animations)
https://www.curseforge.com/minecraft/texture-packs/fresh-animations
BetterBiomeBlend (and less lag too)
https://www.curseforge.com/minecraft/mc-mods/better-biome-blend
BetterF3 (F3 is labelled and organized)
https://www.curseforge.com/minecraft/mc-mods/betterf3
ClientTweaks (various QoL tweaks)
https://www.curseforge.com/minecraft/mc-mods/client-tweaks
Dynamic Music (Dynamic in-game vanilla music)
https://www.curseforge.com/minecraft/mc-mods/dynamic-music?page=2
FarSight (more view distance without perf loss)
https://www.curseforge.com/minecraft/mc-mods/farsight
Inventory Essentials (QoL tweaks for moving items with mouse)
https://www.curseforge.com/minecraft/mc-mods/inventory-essentials
InventoryHUD (Some nice customizable QoL HUD icons/text additions)
https://www.curseforge.com/minecraft/mc-mods/inventory-hud-forge
JourneyMap (More customizeable minimap, includes cave mapping)
https://www.curseforge.com/minecraft/mc-mods/journeymap
Notes (you can write notes in-game for stuff)
https://www.curseforge.com/minecraft/mc-mods/notes
SmoothBoot (Minecraft no longer holds your PC hostage during startup)
https://www.curseforge.com/minecraft/mc-mods/smooth-boot-forge
SoundFilters (nice echo reverb effect in caves and places)
https://www.curseforge.com/minecraft/mc-mods/sound-filters