Please enable 'custom' frame rate option on export settings,
so that users who are editing for example source footage
coming from 8mm or 16mm based on frame rates like 16fps or 18fps,
can export them to such frame rates or other.
you can check the thread here:
https://community.adobe.com/t5/premiere-pro/export-18fps-sequence/td-p/10486209?page=1