Can you imagine playing poker with someone who says that if *they* win then you have to pay up, but if *you* win, they will say the game was rigged and refuse to pay you?
Because that's where we are in American elections today.
No, it's not. Both sides must agree to rules of the game that are fair and transparent. Strictly enforced, agreed upon rules. Otherwise, that is when the outcomes are not trusted. In 2020, blue states changed rules for mail in ballots, signature checks, drop boxes, etc.