“other” storage

Keeping in mind that the “other” storage category is mostly filled with cache and system files created by Safari, the Mail app, other apps and iOS itself. That space is automatically managed by iOS and you can’t interact with it.

That said, start here: Clear Other storage on your iPhone or iPad - Apple Support

If the issue still persists, some benefits to reduce that space can be also obtained creating a full backup of your device, then restoring it to factory settings and, in the end, setting it up as new, as per these instructions: Restore your iPhone, iPad, or iPod to factory settings – Apple Support

When done, restore data from your previously made backup, then restart your device and

check your device storage again.

For any further help, contact Apple Support directly, using this link: Get Support

Regards

Giulio

Update to iOS 13.6.1.

Clear Other storage on your iPhone or iPad - Apple Support

Edit - wow, you are fast and thorough Giulio!