I downloaded this action and tried it and it does work with PSE 2020. Thanks for that link Helen. It provided a straight three rectangle panel triptych so give it a try whippet. It's really easy and once you have run it you can place a texture of choice for the background to the triptych and your done.
Lillias PSE 11,13,15,2020 Topaz Studio 2 Smart Photo Editor 64 bit Windows 10 Home