The List object can be configured to include Action Plan functionality. In this article, we'll review how to add a button to the Lists page layout so you can start utilizing Action Plans. Please familiarize yourself with Action Plans prior to activating this feature by reviewing this article.
1) Go to Setup.
2) Select Object Manager.
3) Use the Quick Find search box on the top right-hand corner. Type in List, then select List from the options displayed.
4) Select Page Layouts on the left.
5) Select the default List Layout.
See the animation below for guidance on steps 6-9:
6) Access Mobile & Lightning Actions.
7) Drag and drop Apply Action Plan in the Mobile and Lightning Experience Actions section of the page.
8) Click Save.
9) Lastly, verify that the button is present when you open one of your existing list records.