Speeding up the footage from 24 fps to 30 fps and slowing from 24 fps to 18 fps

I'm editing a feature film which was filmed mainly at 24 fps.   I have an action scene filmed at 24 fps which i would like to speed up to 30 fps to imitate a normal speed. I was told that if I will have this final movie in 24 fps (as I guess most distributors want...) , then all the clips converted to 30 fps will be converted back to 24 fps when i export the final product. So is there any realistic way to have the action scene in 30 fps although most of the rest of the movie would be in 24 fps ? if so, how ?

Second question : I have a drone footage shot at 24 fps where the drone moves forward too fast. Can I slow it down to for example 18 fps in post production ? Thank you.