How to decrease “other” in storage

• Other: Non-removable mobile assets, like Siri voices, fonts, dictionaries, non-removable logs and caches, Spotlight index, and system data, such as Keychain and CloudKit Database. Cached files can't be deleted by the system.
• System: Space taken by the operating system. This can vary based on your device and model.

About cached files in "Other"

Finder and iTunes categorize cached music, videos, and photos as Other instead of actual songs, videos, or photos. Cached files are created when you stream or view content like music, videos, and photos. When you stream music or video, that content is stored as cached files on your device so you can quickly access it again.

Your device automatically removes cached files and temporary files when your device needs more space.

If storage on your device differs from what you see in Finder or iTunes

Since Finder and iTunes categorize cached files as Other, reported usage for Music or Videos might differ. To view usage on your device, go to Settings > General > [Device] Storage.

If you want to delete the cached files from your device

Your device automatically deletes cached files and temporary files when it needs more space. You don't need to delete them yourself.

How to check the storage on your iPhone, iPad, and iPod touch

In short --> Restart the device. That's it.

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.

Some benefits to reduce that space can be 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.

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

Regards

Giulio