The “President” did not go to court, it was the “Trump campaign” and several states and legislators. He did not exert the DOJ or FBI to secure the required hard evidence of computers, FBI interviews, court warrants etc...
After the election but they sued in several states before. They tried to stop the extended mail in ballot deadline in PA and the universal mailing of ballots in NV.
They lost in NV because it was the legislature who voted for the changes