IIRC they also just recently launched a new setting that allows you to permanently set the target resolution for all games (this might still only be in the beta branch though).
Previously you had to go into each game’s settings from Steam, and change the resolution there (which might be how you missed it).
Oh wow, I didn’t expect another release so quickly! Props to the COSMIC team! I can’t recall where the roadmap for the features and their targeted releases went, but I hope we can get Night Light/Blue Light filtering soon.
I also did not know they had a Mastodon account, thanks for the shout so that I could give 'em a follow.