Editing Bookmark Cards

Hope everyone is safe & well.

Could someone point me in the right direction with Bookmark Cards.

Firstly, I’d like to change the length of the excerpt on the card.

Secondly, I’d like to change/control the font size of the ALT text for the card.

Both highlighted on the image below.

If possible I’d like to use the code injection feature either on the specific page or in the overall theme admin.

Thanks in advance.