How can I add Action Buttons on a Record Page?

With “Visible Action Buttons” setting in Lightning App Builder , Salesforce Administrators can modify the number of Actions that show on the page. There are 2 points you will need to consider though:

This functionality is only supported on the desktop version in Salesforce
The maximum number of Action buttons is 10.

Follow my steps.

Step 1: Click a record from an object (e.g. Opportunities)

Step 2: Click “Edit Page”

Step 3: Click on “Highlights Panel” and add (or decrease) the number of “Visible Action Buttons”. Once done, click anywhere outside the box and then click on “Save”