If you like single player adventure the first game you need to get is Mario Odyssey.
The new castlevania came out recently if you’re into that. Also, dead cells is a similar game that you would enjoy.
Super Smash bros is a must have.
So is Bayonetta
They have Skyrim for the switch which is a fantastic game even if it is pretty old.
You’ve got tons of great games on switch for different moods: Mario kart, Mario maker, xenoblade saga, final fantasy7,8,10, Mario tennis, puyo puyo Tetris, doom (which plays phenomenally on switch), and Starlink is an excellent spiritual successor to Star Fox