The premise here is that Trump loses but refuses to back down, attempting to forcibly claim victory. If Trump legitimately wins, there is a different path. Then…
Assuming multiple systematic failures occur simultaneously, including any of: actual voter fraud, fraudulent electors, congress refusing to certify, a captured supreme court acting in favour of Trump, or actual insurrection on or before Jan 6th.
I actually expect the US Military to step in. Every member is sworn to uphold the constitution. But if the constitution has been discarded, then I’d expect them to step in to restore it.
Failing that, the US likely fractures and we leave the Republic phase.
Depending on the carrot, the skin can be significantly more bitter. And sometimes peeling can be quicker than trying to scrub dirt out of particular lumpy carrots.
YMMV