Solution:
- Back up your phone (iCloud or Mac/PC)
- Restore your phone to factory settings
- Restore your phone from a backup/iCloud when prompted
Even though you make the backup with the trash data, it's cleared out during the restoration. For reference, even though my Maps file was just over 12GB and I only had ~2GB free at the time I started the process, I ended up with 35.64GB of free space. It seems there's even more garbage data clogging our phones. I hope this helps!
Edit: Adding that this was verified as the solution by the Apple Support team. I had to escalate to a specialist and discussed what I had done so far.