Yes but unless you practice on the appropriate platforms per the game it's just casual at best play.
I've got a ton of friends and by far the simplest way is to in-game and/or in-lobby compliment the other players and play good then send the Player(s) Friend requests via Steam. Generally speaking 1 KDR players friend 1 KDR players, as do 5 KDR players and so on. IF you have a VAC Ban then no legit player nor especially a Clan will accept your request and 9/10 block you instead.