Whenever Donald Trump loses an election, he is going to accuse his opponent of cheating. The facts do not matter. Republicans will always fall in line behind Trump when he makes these accusations of cheating, even when they have been made against a fellow Republican, such as Ted Cruz following the Iowa Caucuses in February of 2016. The question facing Republicans right now, is not whether they cheat, but whether or not they will ever have the backbone to stand up to Donald Trump.
As a possible hypothetical scenario, let's say that Ron DeSantis decides to run for President in 2024, and Donald Trump decides to run as well. Here are two pertinent questions for Republicans :
1) Under this scenario, if Ron DeSantis was to win the Iowa Caucuses in February of 2024, is there any doubt that Donald Trump would accuse the DeSantis campaign of cheating, and completely blame his loss on fraud, regardless of whether he could prove that or not? Try to be honest with yourself here. What does Donald Trump's track record suggest that he would do?
2) ... and is there any doubt that Republicans in Congress would fully support Donald Trump with his accusation against the DeSantis campaign, and make appearances on Fox News to help him undermine those results in Iowa?
Basically, Republicans don't have a problem with cheating. Republicans have a problem with missing backbones.