You can use the advanced search to find mails larger than X.
Also if you're not aware, Google Photos lets you downscale photos and videos so they don't count towards your quota at all. See "Recover storage" on https://photos.google.com/quotamanagement
Thank you. I’m aware but I’m referring to what they show on their actual clean up tool attached to the you’re approaching your storage limit message. It’s an infuriating dark pattern.