Apple must give power users more control over this feature.

Using High Sierra, I disabled Local Snapshots approximately nine months ago as a test, and enabled them again after a few weeks. No problems at all, but it is possible that more recent updates to High Sierra have changed things up a bit and new commands may be necessary.

Since Time Machine is part of the Mac operating system, you will likely get a faster and more informed answer if you post over in the support forum for High Sierra......where the operating system gurus hang out. Good luck.

macOS High Sierra

You have posted your request on a forum for users. We are all users here......just like you. No one from Apple is here, and it is extremely unlikely that anyone from Apple will ever see your post.

If you want to contact Apple, you can do so here:

Feedback - Time Machine - Apple

As far as gaining "more control over the local snapshot feature", there are any number of articles on the Internet with instructions on how to do this. For example.......https://www.imore.com/how-us-time-machine-local-snapshots-recover-data-your-mac- laptop

To disable local snapshots in Time Machine and remove them from your internal storage:

1. Open Terminal on your Mac laptop.
2. Enter the following command into Terminal:

   sudo tmutil disablelocal

3. Press Enter.

This will remove those local snapshots from your internal storage. You can then re-enable the feature in Time Machine (which I highly recommend).

1. Open Terminal on your Mac laptop.
2. Enter the following command into Terminal:

   sudo tmutil enablelocal

3. Press Enter.

Proceed at your own risk.

I'm a novice in this kind of matter, but you could see this thread: macOS High Sierra – Huge System Storage