Trump is currently exploring how (not "if") he can activate the US Insurrection Act of 1807. (https://en.wikipedia.org/wiki/Insurrection_Act_of_1807) and he wants to do it as quickly as possible.
https://www.msnbc.com/news/news-analysis/trump-national-guar...
If he does he can (and will) federalize all National Guard units so they in fact become "federal troops" and this can (and will) allow his "own" federal military through Hegseth to deploy and operate domestically. Additionally he can declare a portion of the US population "insurrectionists" and act upon it, without interference of local law enforcement and government (and the risk of also labeled the same if they do).
As a European with quite some knowledge about European history hopefully I do not have to take a history book and explain the repercussions of Trump doing this?