He would be sharing that honor with 2 other holidays, good ones to go along with his former Presidency if you ask me.

"People across the United States celebrate Flag Day on June 14 each year to honor the United States flag and to commemorate the flag’s adoption. On the same day, the United States Army celebrates its birthday."

https://www.theepochtimes.com/ohio-republicans-propose-designating-june-14th-as-president-donald-j-trump-day_3678472.html