Can this iphone receive iso 13.5 6s

That model can be updated to 15.5. It's no longer possible to update to exactly 13.5.

(219547)

Assuming you actually have a 6s, you can update to the current version, 15.5.

If it’s running 12.5.5 and software update says it’s up to date, it is not a 6s.

Yes it definitely can!

Supported iPhone models - Apple Support (PH)

You can also update it to 15.5

Hope that helps