for sure. As you mentioned, in the search feature you will search your entire source which is currently selected.
If you are inside a playlist, your sorting is maybe set to “playing order”, you are able to change the sorting to “Key” - search for your specific Key, do somethings and change back the sorting to “playing order”. In this case, you just gonna change your sorting of the current selected playlist you’re in.
In the search feature (not playlist), you are also able to do a search combination.
If you are using specific tag fields in your musfic files to sort or find music, you can filter on some tag fields like artist, comment, label, with a specific value before choosing one of the search lists (Artist, Title, BPM, Key, Genre).
Basically what this amounts to is a “smart playlist” which changes based on various parameters - and smart playlists were requested a very long time ago.