How to Change SharePoint Online Task List to Modern Experience?
Task lists in SharePoint Online are created with Classic experience by default. To change its UI to the new experience user interface, do the following:
- Go to Task List settings >> Click on the “Advanced Settings” link
- Scroll down to the bottom, and from the “List experience” section, select the “New experience” option and hit OK.
If you want to set the list to new experience using PowerShell, use: How to Change the List Experience in SharePoint Online using PowerShell?