brand new MacBook Neo system data is over 300gbs

Here are some things that you can do everyday to manage your free space:

• Reboot your Mac at least weekly. Let the OS do housekeeping and clear caches.

• Empty the Trash in the Dock. 

• Empty the trash in the Photos app.

• Delete unused and unneeded application installers from your downloads folder and desktop. No need to store on your Mac what you can freely download again any time.

• Transfer files that you don’t use daily to an external drive and then delete them from the startup drive and empty the trash. Files that typically take up the most room are movies, images and music.

This from Apple on the subject of freeing up space:

Free up storage space on Mac - Apple Support

Find and delete files on your Mac - Apple Support

And this user tip: How to Use Finder to Clear “System Data" on a Mac (Thank you, @TheLittles!)

If you have enabled Time Machine to back up your Mac automatically but do not keep your backup drive connected all the time, then MacOS keeps a number of Time Machine snapshots on the drive as part of the backup process.  These TM snapshots can occupy a significant amount of drive space. You can disable the creation of these many TM snapshots by setting TM to backup manually rather than automatically at intervals.

You can view and manage these Time Machine snapshots in Disk Utility or in the Terminal app. View APFS Snapshots in Disk Utility on Mac - Apple Support 

You can also use apps such as Storeograph from Etresoft, Inc  or OmniDiskSweeper from Omni Labs  to find the large files on your drive.  Once you've located these larger user files, you can relocate them to another drive and/or delete them if they aren't needed.

Just to add to the Great Work done by my colleague @ D.I. Johnson

Looking that your presented image from System Setting >> Storage

That is "Eye Candy" that is highly inaccurate, not a true representation of the storage actually " used " / " free "

Suggest using Disk Utilities located in Finder >> Go >> Utilities >> Disk Utilities

1 - From another contributor @etresoft regarding Free Space and Available Space 

Free vs available disk space huge differe… - Apple Community

Quote >>  “ The "available" storage is the amount of used storage that the operating system could automatically delete if it felt that it was really necessary. The "free" storage is the amount that you can actually use for something.

There are system processes that run in the background and automatically delete some of the "available" storage and convert it to "free". If you completely run out of storage, then those system processes will try a little harder. When you "delete" files you are just hinting to the operating system that you don't need those files anymore. The operating system will eventually remove them, but on its own schedule.

Certain tools will allow you to force the issue and manually clean up some of this storage and manually delete local snapshots. But that is only temporary. "  << End Quote 

2 - Purgeable Space is controlled by the Operating System and not the user 

Get detailed information about a disk in Disk Utility on Mac

1 - To see the Time Machine Backup Snapshots and if there are any

Use the information from @ D. I. Johnson 👍

If it was missed and this can happen, here it is again

You can view and manage these ➡️. Time Machine snapshots ⬅️. in Disk Utility or in the Terminal app. View APFS Snapshots in Disk Utility on Mac - Apple Support 

2 - The worse of the worst option and as a Last Resort

Start Over from Scratch 

Heavy Handed ?  - Yes 

Effective  ? - Yes 

For Apple Silicon computer >> Use Disk Utility to erase a Mac with Apple silicon.

Use the Erase All Content and Settings feature to quickly and securely erase all settings, data, and apps, while maintaining the operating system currently installed.

Always make a Time Machine Backup  before  proceeding 

Emphasis on User Account Only

Follow on and I stand to be corrected

What I do see in you image above

Is the  sealed and read-only volume which is where the operating boots from

That can not be opened, modified, altered or otherwise be delated

Not by you or me or any Third Party Application

Whatever you do,do

DO NOT use any Third Party Cleaner my any brand or name

Any Third Party Applications that will interfere with the normal operation of the OS,  is an invitation for disaster. 

Certain Applications maybe available on the Apple Apps Store like CleanMyMac and other - this only means the Developer is prepared to pay Apple a percentage on each sale. 

Any of the below should be removed as per Developers Instructions 

Disk Cleaner 

CleanMyMac , aka “ BrickMyMac “

New macOS Malware "Cthulhu Stealer" Targets Apple Users' Data

MacKeeper,

Dr Cleaner Pro Plus

Open Cleaner one Pro

Macmechanic

Clean my Mac x.

MacBooster

Macscan

MacCleanse 

CCleaner 

MacCleaner 3 Pro

UUbyte CleanMateUUbyte CleanMate

Great work there my friend

🦉- 53