Trump is already disqualified from holding any office, let alone that of the President, under section 3 of the Fourteenth Amendment.

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4591133

Page 17:

V. The persons who framed Section Three of the Fourteenth Amendment regarded the President of the United States as an officer of the United States

The President of the United States was among the officials who took the oath to the Constitution that under Section Three triggered disqualification for participating in an insurrection. As noted in the previous section, the persons responsible for the Fourteenth Amendment sought to bar from present and future office all persons who betrayed their constitutional oath. “All of us understanding the meaning of the third section,” Senator John Sherman of Ohio stated, “those men who have once taken an oath of office to support the Constitution of the United States and have Fourteenth Amendment distinguished between the presidential oath mandated by Article II and violated that oath in spirit by taking up arms against the Government of the United States are to be deprived for a time at least of holding office.” No member of the Congress that drafted the the oath of office for other federal and state officers mandated by Article VI. Both were oaths to support the Constitution. Senator Garrett Davis of Kentucky saw no legal difference between the constitutional requirement that “all officers, both Federal and State, should take an oath to support” the Constitution and the constitutional requirement that the president “take an oath, to the best of his ability to preserve, protect, and defend the Constitution.” Senator James Doolittle of Wisconsin declared that Congress need not pass laws requiring presidents to swear to support the Constitution because that “oath is specified in the constitution.”

In fact, the exact question of whether the disqualification from public office covered the Presidency came up at the time the Fourteenth Amendment was being drafted: https://crsreports.congress.gov/product/pdf/lsb/lsb10569

Specifically:

One scholar notes that the drafting history of Section 3 of the Fourteenth Amendment suggests that the office of the President is covered:

During the debate on Section Three, one Senator asked why ex-Confederates “may be elected President or Vice President of the United States, and why did you all omit to exclude them? I do not understand them to be excluded from the privilege of holding the two highest offices in the gift of the nation.” Another Senator replied that the lack of specific language on the Presidency and Vice- Presidency was irrelevant: “Let me call the Senator’s attention to the words ‘or hold any office, civil or military, under the United States.’”

I’ll highlight that last bit again:

Another Senator replied that the lack of specific language on the Presidency and Vice- Presidency was irrelevant: “Let me call the Senator’s attention to the words ‘or hold any office, civil or military, under the United States.’”

That is from this paper: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3748639

Some people seem to have a lot of trouble with figuring out what “or” means, in a list of things.