You can customize the action icon displayed on your tiles to better match the look and feel of your site. Use any image as a custom action icon to give your tiles a more personalized appearance.
To add a custom action icon:
In the site editor, select the media tile where you want to add a custom action icon.
Click the Action tab.
Under On Click, select Show Action Icon.
Select Custom Icon.
In the Media Library window, search for the image you want to use, then click Select.