Okay, I'll take your word for it the OP was in no way inspired by Trump and is entirely a rhetorical question.
That being said, IMHO worrying about "fascism" is completely overblown unless/until truly exceptional circumstances exist such as:
1. The government starts taking actions or policy positions that are way outside any historical norms and precedents absent some truly exceptional circumstances like the immediate aftermath of 9-11. Not just "way to the far end of the liberal/conservative spectrum" but completely off the spectrum chart altogether. Like suggesting that all firearms be confiscated, or that sharia or other religious laws be implemented, or that core civil rights protections were no longer valid for all citizens or entire classes of people.
2. Key government officials rewrite laws to entrench themselves or eliminate restrictions on their powers, such as seeking to get the 22nd Amendment nullified so the POTUS could run for additional terms.
3. The POTUS starts routinely asserting the separation of powers or checks and balances no longer applies or should be weakened systematically and across the board (not minor tweaks like suggesting line-item veto)
4. POTUS uses his inherent powers to attempt to make the executive "above the law," such as applying prospective blanket pardons to his cabinet members and then ordering them to take illegal actions under the logic they can't be prosecuted for them given the pardons in effect.