How to Ensure Full-Size Images Display Consistently on Slack Companion Sites Using Block Kit

hey team, is there a way for the images you post in slack to show on the companion site in full size the same way as if you were to use slackblock kit builder? sometimes on the builder ill get full sized images & therell be times the the image is half cut off and says "see more" is there a correct way to upload images to get them to look consistent?