Hi there,
I agree with the questions asked on the why, though is it possible? Sure! Do you need to clone and edit the widget as suggested in one of the replies: NEVER ever do that for a requirement like this, that's a horrible practice! Just CSS override, nothing more.
Here is a started for you, an article I wrote 4 years ago. If after reading this still help needed, just post a reply.
- 2020-05-18 - Article - Changing Service Portal widgets look and feel without cloning widgets
