That is impossible to believe. No one would vote Republican down ticket and NOT for Republican for President.
That happened a lot in 2016. Don't know about this time.
I have had quite a few Dims suggest this to me, that Republicans hate Trump so they voted for Biden, and then down ticket for Republicans which is why Biden had no coattails, and not that there were many millions of likely fraudulent ballots marked only for Biden/Harris. They tell me that the GOP base just hates Trump.
Three things you need to tell them, first of all, Trump received approximately 70 million votes, and there are approximately 55 million registered Republicans in the country so not only did the president receive basically all of the GOP votes, but a great number of Independent and Democrat votes.
Secondly, if you look at the number of votes Trump received in any given state, you will see that the numbers of votes down ticket are roughly the same.
Third, usually the Republican voter who loathes a GOP candidate it is because there is so little difference between the GOP and the Democrat candidates, and in the end will decide the GOP is slightly less objectionable. In those cases when the GOP candidate is so reprehensible, the voter can’t bring himself to vote for that candidate, he will cast a protest vote for the libertarian candidate if there is no Constitution Party or other conservative party candidate.
Ordinary grass roots Republicans do not vote for Democrats even if Jeb Bush, et al, do.
I close with telling my dim friend, that republicans are not like democrats at all, we think very differently than they do.