Can you guys recommend some good CO-OP online games?

old but god left4dead 2/portal 2 or sniper elite v3/4 good stuff

Portal and Borderlands series, can't go wrong with those.
I have also enjoyed playing Dying Light with friends before.

Payday 2 is fun, however it can be really frustrating at times.

Rust, overwatch, escape from tarkov, COD Warzone, PUBG and fortnite. Depends what gaming style you are looking for.

Portal 2 is way too good to not be played honnestly.

There is also the halo saga which is coming on pcc ( Halo 3 i'm waiting u my buddy)

Don't Starve Together, Division 2 (if you wanna fight another pandemic world...), Stardew Valley, Borderlands 3, Sea of Thieves, Minecraft

Random assortment of various genres and types for good coop stuff

I love a lot of these suggestions! Stardew valley is especially fun. But just be warned that everyone you play with has to be on the same platform. My friend has it on the switch, and I can't play with him haha..

Overcooked 1 and 2 are fun too, but I'd recommend finding at least a third player.

Street of Rage 4 just released gogogo ! it's really fun with friends!

left 4 dead 2 or 1 borderlands the forest payday 2 and for honor singleplayer but coop 2 player

Apex Legends is fun if you like FPS and battle royales, even has duos now