Yes, you should have no problems:
https://winscp.net/eng/docs/installation#upgrade
Unless the user connects to some very obsolete servers that needs insecure algorithms not supported by the latest version of WinSCP.

---

Rare incompatible changes are documented here:
https://winscp.net/eng/docs/incompatible_changes

You can always downgrade, if needed.

Hello all.

Is WinSCP backwards compatible?
We need to upgrade WinSCP version for a customer for a new site (uses private key). Customer uses several other sites that do not need new version of WinSCP. Will the latest WinSCP work for all sites, should it not?

Thanks