Will the saved data of downloaded games be deleted if you delete the game?

I have a question about the Nintendo switch, I wanted to get a new Micro SD card, but there's still game data on the other one. Can I delete the games without the game data being gone or if I delete the game, the saved games are also gone

No, the saved data is retained. You will also be advised of this when deleting the game.

Depending on the game and Nintendo Switch online membership, the data is even backed up online.