I agree with Ann. Fixed frame rate is usually better for editing in any editor.
That said, PrE 2021 is supposed to work with variable frame rate footage from phones. I've tried it and it will, depending on the source. 30.08 fps is not common! So, consider trying it! It may work fine.
You can't change it in General Settings once the project is underway. It is supposed to automatically pick the appropriate settings when you put the first clip on the timeline. It usually works!