If you want to stream games from your PC to the Steam Deck using RemotePlay, you need to follow the steps mentioned in this post.

Check out how to use Steam Remote Play Together for full instructions on how to invite your friends to play local co-op games with you. Taking Screenshots In-Game and Uploading Them to the Steam ...

but using Remote Play is an easy alternative. It can also be found on a game's store page under the small Steam Deck Compatibility section between supported languages and in-game achievements.

Since the launch of the Steam Deck (and many other handheld gaming consoles), players now have a portable gaming solution for PC games. Still, Steam's Remote Play feature allows you to stream ...