Sorry, I was wrong. It needs to be on the html.
Here's the steps to create:
- Add ID onto element at top of page (eg: top-link)
- Add html embed with <style>html {scroll-behavior: smooth; }</style>
- Create link at bottom of page (place with fixed or absolute position) link it to the "top-link" target on the page
- You might need to publish to see this work