I guess the question to ask in regards to presidents and abortion is, do presidents have anything to do with it?
Reagan and Bush were both very pro-life, but did they get abortions outlawed or even moved to being a state’s decision? Would Johnson or Paul veto anti-abortion legislation? That to me would be the important question. But I doubt it would ever get to them, even if we had both houses. It is a topic that politicians use on the trail, but dont put much effort into in office.
Presidents are crucial to the abortion question. They nominate the Scotus justices.
Of course, they have the bully pulpit, they can influence the submission of legislation, etc.
But there is no authority more important in this debate than the Scotus.
(Unless Congress some day decides to actually use its constitutional authority to tell justices what to do.)
That's because there isn't a whole lot they can do about it once they get in office.
The only real leverage politicians have is appointment of judges to SCOTUS and voting for their confirmation.
Overturning Roe v Wade is next big step. And that's up to the judges, not the politicians.