Steam Deck quick setup for offline play

Hi.

I expect to be getting Steam Deck for Christmas and I want to be able to play offline soon after, on a plane. I can set everything up online but then I really hope it's going to work offline during the flight.

I plan to play: Baldur's Gate 3, RDR2, maybe Witcher 3 and maybe something else (Outer Worlds?) oh and maybe Fallout 4.

From reading the other threads I may need to launch RDR2 online and then it should continue fine w/o Internet, for other games I hope they are going to work fine in offline mode?

Should I launch them all online , check for updates etc and then switch to offline, what's the recommended procedure here?