First depends on the size of the moon, if its like the size that it realistic then there’s no need to make it round and set up a flat area and you could use the landscape tool (its next to the basics tab on the top left area of the editor) to try and make it look like the moon. Also play around with the editor epic has a few good startup tutorials for getting your feet wet. Some more than others also if you wanted it to have a moon material and everything, sorry but your gonna have to texture it. Again play with it, just don’t delete any files that’s built into the engine and you should be fine!