Yes, this is source transitions! If you'd like to play around with it yourself there is a pull for it on the OBS github. https://github.com/obsproject/obs-studio/pull/1905
If you wanna be able to officially do stuff like this in OBS, please upvote here: https://ideas.obsproject.com/posts/10/allow-for-source-specific-transitions
Chitter is a social network fostering a friendly, inclusive, and incredibly soft community.