I've used most available services, but discontinued one after another along with promises that a better user experience will be provided with reduced content and removed functionality with the slight price hike. YouTube was my first and last video service I paid for, only Spotify remains on the borderline.
YouTube ReVanced supports setting a default video resolution for mobile and wifi networks.
But make sure to only download from the official site or their github. The top search engine results are not be trusted third parties.
https://github.com/revanced
https://revanced.app
mahalo!