Earlier today I added some CSS code that changes the caption size on older images (Pre-GP). Now trying to figure out how to do it for GP image blocks.
Here’s a GP image with caption:

The caption size is not changed from regular text. Changed using Typography setting on the block. Not a global option.
Sent a request to GP Support 1/28/24.
Here’s a native WP image with a caption

The caption is smaller, as set by the CSS code.