How to get the Max Viewers of an Game out by Streamers, and specify wich one?

API
3

This endpoint doesn’t support the parameters you have specified

This is no sort control. Generally the streams are sorted by view count anyway

To perform a lookup by game, you’ll need the game_id for the game as documented

game_id string Returns streams broadcasting a specified game ID. You can specify up to 100 IDs.

The Games API is documented here

So

https://api.twitch.tv/helix/streams?first=1&game_id=123&language=de

Assuming you want german from your original URL