To inject a bit of nuance here, I think a more dynamic approach to sexual consent would actually be a good thing - not to lower it, obviously, but rather instead to protect more vulnerable people. The idea that kids just stop being vulnerable to coercion at 18 is honestly kinda stupid to me, I think instead we should have a less clear-cut barrier and if there is an issue it should come down to a court opinion, taking into account other kinds of power imbalances - such as wealth disparity, abusive power dynamics (say, between a professor and a student, or a boss and an employee), disability, etc.

People in a position of authority shouldn’t feel legally safe just because the person they’re abusing is over the age of 18. The burden of consent should be higher in such cases. Just in my opinion.

Now the cut-off age is used as a threshold, after which presumption of innocence is kicking in (sex between adults is consensual until proven otherwise).

In your proposition there would be no such threshold?