Synchronizing table cells from different files?

Question

Data synchronization

Requires dynamic synchronization of the specified cells from one Google spreadsheet to another file with a Google spreadsheet.
For example, if data changes occur in File 1 (sheet 1) in cells A1, then a corresponding change occurs in file 2 (sheet 1) in cells A1.
In addition, the import must be two-way.
What if in a similar way there were changes in file 2 (Sheet 1) A1
, then the same change occurs in file 1 (Sheet 1) A1.
There is also a requirement for the script that the cells are customizable.
For example, synchronize file 1 (sheet 1) A1 with file 2 (sheet 1) B1 or C3, or J8, etc.