The way I usually handle lots of modpacks is to make a new mod folder and shortcut pointed at each mod folder. Then all you need to do is click on the shortcut and it only loads the mods for that modpack. No need to restart to sync mods. The downside of this is that you might have duplicate files across the mod folders (storage is quite cheap these days though). I especially like doing this as I get involved in modded multiplayer games again to quickly get to the game without restarts if I'm jumping between mod sets often.

i launch the game through steam just a habbit that i cant break, and its also a useful container to easily download all the mods of a certain mod set with it, as well as acting as a single mod for dependencys of other mods. Im using them for my modpack im working on trying to get way to many mods to work toogether https://mods.factorio.com/mod/nach0_modpack main stapels are 5dims, bz, space exploration and krastorio 2, plus a bunch of other stuff

thankfully SE, K2, and BZ already work together :)

yes but 248k which i have added crashes when you pair it with k2 and have the overhaul mode enabled, and ive added 5dims which adds recipe and tech problems as well as a bunch of other mods that cause general streamling issues