here is a post that explains what 'other' storage is
What is "Other" and What Can I Do… - Apple Community
Note that when you delete photos/videos they go to a 'Recently Deleted' album where they may be classified as 'other'. Try deleting them from there and see if 'other' storage drops.
You an also check the Files app and see if there is anything in the Recently Deleted area.
If you haven't updated to the latest iOS (currently 13.6), it wouldn't be a bad idea to do so if you have the storage space available to do an update.
Update your iPhone, iPad, or iPod touch - Apple Support
If all the Recently Deleted areas are empty, try a force restart
Force restart iPhone - Apple Support
If you continue to have issues:
You can use the Contact Support link in the upper right of your screen so that Apple can troubleshoot 'Other' storage issues on your device.
Get Support
OR you can do the following:
Backup/Reset/Restore your device, review these links:
How to back up your iPhone, iPad, and iPod touch - Apple Support
Restore your iPhone, iPad, or iPod to factory settings - Apple Support
Restore your iPhone, iPad, or iPod touch from a backup - Apple Support