Using Preview to adjust photo to a specific size
I am using Big Sur 11.4 on a 2017 iMac
I have a photo that I would like to print as an 8x10. This site doesn't show me the image that will be printed. I thought the photo would be the same image as displayed on the iMac in Preview, but it automatically crops the photo for me and it isn't what I would like. I would like to crop the photo myself or have the full image print ideally. The photo dimension is 3000 x 1489.
I have googled and watched YouTube, but I can't seem to find this specific scenario. I have looked at Tools and adjust size, but get confused at that point.
Any help would be greatly appreciated!
iMac 27″, macOS 10.13