How to resize the Cover block?

Non coder question, just trying Gutenberg for the first time today:

Is there an easy way to define block dimensions? I’m using the Gutenberg Cover block for a post header, and it looks pretty good. Horizontal is fine at the full-page width default, but vertical is too tall for my needs.

Not knowing enough about the back end, I’ll also ask if code, theme or page builder are the more appropriate areas to deal with this? I’m using Elementor page builder with the OceanWP theme. And if I do have to mess with code, can someone just point me in the right direction?

Thanks!