A plugin built on 10.11 should be forwards-compatible with newer versions of macOS. The main potential issue that springs to mind is signing and notarisation. Newer macOS releases require installers and plugins to be notarized. Although it’s still possible to use non-notarized installers/plug-ins on these platforms, the software will display a warning on first launch and must be explicitly allowed in system preferences. Notarization will allow your users to avoid this awkward first-time setup.
This page provides some more detail about the notarization process. There are also some useful threads on the topic on this forum.
It definitely works for installers, but I’m not sure about plug-ins. According to the link above, it sounds as though on Catalina onwards, quarantined plug-ins will need to be enabled in System Prefs before they will open.