The only possible way to change election laws is to actually win elections and then change the laws.
If the election system in certain places is crooked, a candidate and party have 2 choices, keep complaining about rigged elections and lose, play the game using Democratic rules and have a better chance of winning.
The problem is they won't let you play by their rules. If you watched any of the election night action you saw that republican poll watchers were excluded from even being in the building where ballots were being counted or maybe held so far away from the ballots they couldn't actually see anything. Many counting stations ignored courts orders to allow closer observation and all without consequence.