Is /private/var/db/dyld/dyld_shared_cache_x86_64h safe to remove?

No it's not safe to remove, and is expected to be present when launching applications. Its directory should not be touched.

To increase available storage space read How to free up storage space on your Mac - Apple Support.

A "Safe Boot" deletes all cache files that can safely be deleted.

I have about the same file size 1.3GB

last updated Jan 24

I would not remove it, it is used to cache info.

If you want to clean some space safely, use

Apple > About this Mac > Storage > Manage

Another simple method is to use Finder sorted by Last Opened date.

There you will find files that has not been Opened by you for very long time, move the out