System is using 127 GB out of 250 GB storage

FYI ... System includes:

• Time Machine local snapshots, but are marked as 'purgeable' and should not be remove manually. However, they can be, as follows:
  • To get a list of snapshots from the Terminal: sudo tmutil listlocalsnapshots /
  • To delete individual snapshots: tmutil deletelocalsnapshots <enter the snapshot>
• Spotlight Indexing
  • How to rebuild the Spotlight index on your Mac - Apple Support
• iCloud Storage of infrequently-used files.

Ref: How to free up storage space on your Mac - Apple Support

Just to verify, is your Mac still running macOS Mojave? If so, which exact version?

Regardless, I suggest that you run an EtreCheck report and optionally post it here so that we can try to assist you with what potentially is using up that much "System" space.

Ref: Using EtreCheck to Troubleshoot Potential… - Apple Community