No, it was already proven there was election fraud against Trump. That's why the statement is now "widespread fraud" or similar wording.
Several people have already been arrested and charged with election fraud or similar acts on both sides.
Being an absolutist on this is harmful and further promotes black and white, all or nothing type thinking regarding the security of our elections.
https://apnews.com/article/voter-fraud-election-2020-joe-biden-donald-trump-7fcb6f134e528fee8237c7601db3328f
Here is one source. There's plenty of news stories if you just search for "democrat election fraud 2020" and focus on individual stories.
Also, are people forgetting about Michigan?
https://factcheck.afp.com/michigan-county-vote-count-glitch-was-not-fraud
From this particular story:
Similar situation claimed in both instances. Rushing to say Republicans are committing fraud makes you no different than the people you're claiming to criticize. These are equivalent stories and situations and you're engaging in exactly the kind of behavior Republicans who pointed to Michigan engaged in.