Increasing the volume of the / data section without repartitioning. Symlinks?

Question

Android

Found on w3bsit3-dns.com an interesting question about an Android phone:

There is a lot of free space on the /system partition, but I want to do without repartitioning (and leave the sitation more "flexible").
How to make some kind of "permanent symlink" on the / system partition with / data and write there, - for example, 2gis maps?

ln -s /system/*папкаГИС* /storage/emulated/0/*папкаГИС*

How best to do it. Is it possible through system.d from magisk? Or which is better?
And will such a folder be writable for regular applications?
Maybe this idea is stupid - offer your options. If there are no specific tips, then please advise what queries to google - I ABSOLUTELY do not understand anything in Linux.

Since the question also interests me and I also don’t understand anything in Linux, maybe there are answers here?