Currently, you can use https://dev.twitch.tv/docs/api/reference#get-all-stream-tags to get all tags, and then manually iterate through to find tags with given names, but this can be slow (2-3 seconds to search for 8 tags in my test using twurple). It would be better to have an endpoint similar to https://dev.twitch.tv/docs/api/reference#get-games, which allows for a name query parameter. Of course, for tags, this would require also including a language parameter for the IETF language tag.