Yes and that sint true. For example we are mikayem pidyan haben which the Avos didnt as there were no kohanim.
They did exactly what we would do if we didn’t have kohanim.
You can’t give examples where the ability to do the mitzvah isn’t there; that’s not the point of the gemara’s statement that the Avos kept kol haTorah kulah.
The best example of them not keeping kol haTorah kulah is Yaakov Avinu marrying two sisters, and the meforshim deal with that kashya without rejecting the gemara.