Then what you're looking for is roughly Squad.

Made by a team that originated as the mod developers behind Project Reality for BF2.

Currently though, it is going through a bit of an awkward phase as they are trying to transition from UE4 to UE5... but the UE4 version is still pretty solid.

Squad has less of an arcady gameplay style to it than BF proper, more milsim or milsim lite, the gameplay systems themselves reward and revolve more around being in a squad...

...fancier kit loadouts are limited for a whole team, takes multiple people to fully operate a tank or IFV, you actually have to be a pilot or crewman class to fly or drive something more conplex than basically a truck, lower TTK as weapon damages are more realistic, but also more fleshed out medical system...

... there are more gamemodes, many of which revolve much more around logistics and setting u0 and defending FOBs, you got AAS which roughly simulates a frontline by preventing the sort of willy nilly flag backcapping from BF games... flags are grouped together in sort of layers, and you can't capture any flag thats more than one layer away from the layer your team currently has...

Whole lotta gameplay tweaks, vehicles tend to respawn more slowly and players respawn more slowly, but anyway yeah, its a sort of hypothetical roughly modern era war setting, tons of factions.

Also I think there is a Starwars themed mod for it lol, there's ww2 mods for it, etc.

...

EDIT: As strongarm mentions, Hell Let Loose and the Arma series are also good choices, I am just biased because I was once part of the Project Reality team, way way back, hehehe.