Yes, this is directly supported. When you create an auto-clip campaign there's a source type: niche (pulls trending long-form in that category) or channel (watches a specific YouTube channel and grabs the newest upload).
Set it to channel, point it at your own channel, and the loop is: you publish long-form → the campaign picks it up on its next run → clips get cut, captioned, and posted to your connected shorts accounts.
Two notes:
- It tracks which videos it has already clipped, so it won't re-clip the same upload. Once it exhausts the channel's recent uploads it recycles oldest-first rather than stalling.
- Schedule the campaign to run a few hours after you typically publish, so the upload exists when it looks.