Some places in iCloud, like Photos and Drive, have a Recently Deleted section, so for some things you should check there at iCloud.com. See this:
If you're missing photos or videos in the Photos app - Apple Support
Basically the above says, for missing images, to look in Recently Deleted and in Hidden. Be sure to check your Library thoroughly-- the pictures may not be where you expect, as dates may have changed. You can use the search field with the date or location. And remember, you can sort the Library by date captured or by date added
If that doesn't work, and you had Settings>Apple ID>iCloud Backup turned on, then you may be able to recover data some data. with Apple's iCloud Backup You should look here:
Restore your iPhone, iPad, or iPod touch from a backup - Apple Support
This is what you do when you buy a new phone, so this safety, if you have it set, requires you to erase everything on your phone and replace it with the backup.
If you don't keep your own backups to an external drive, then there really isn't any place else to look.