@Tamras1972 Unfortunately, No. You cannot customize UI of SharePoint out of the box highlighted content web part.
You will need to develop your own web part using SPFx for any customizations.
Please click Mark as Best Response & Like if my post helped you to solve your issue. This will help others to find the correct solution easily. It also closes the item. If the post was useful in other ways, please consider giving it Like.
For SharePoint/Power Platform blogs, visit: Ganesh Sanap Blogs