Presidential use of the autopen is not illegal. And Trump admitted that his staff uses the device to mimic his signature on letters.

Donald Trump has signed a Presidential Memorandum ordering his administration to investigate whether former President Joe Biden was really running the United States

Donald Trump has issued a Presidential Memorandum directing his administration to probe whether former President Joe Biden was truly in charge of the United States, or if key White House aides were involved in a "conspiracy" to usurp executive power due to his perceived "cognitive decline".