Good evening Loren and welcome back!
Thank you for reaching out to us.
We are sorry to hear about the featured image size not meeting your expectations.
I would love to help you with this topic.
There are a couple of ways to go about fixing this (depending on your situation).
The simplest way would be to modify your medium image size as defined in Settings > Media (e.g. 1000 x 452).
Once you do that, you can then simply force thumbnail generation using a plugin such as: https://wordpress.org/plugins/regenerate-thumbnails/
The downside to this approach is that ALL of your medium images will now have that size (which might not be what you want).
The other approach would be to add a snippet to your theme’s functions.php file to force a default featured image size. You might want to take a look at the following to get a sense of how that works: https://wordpress.org/support/topic/set-featured-image-size?replies=2
Let me know if that helps.
Have a great day!
Geoff B.