Maybe the problem is your ATV resolution is not matched to the TV’s native resolution. If your TV is 4K, go to settings > audio & video and choose 4K (or 1080p or whatever it should be.) This shouldn’t cause a cropped image, but it’s worth setting correctly anyway, so check it.

You can try audio & video settings > Adjust for Airplay Overscan (check that it’s not on or off. Try toggling it on and off.) But this is unlikely to be the problem unless it was accidentally turned on.

Check that Accessibility > Zoom is not turned on. Try toggling it on and off. Same as above - unlikely, but make sure it’s off.

Now that that’s all sorted, it’s time to actually fix the problem:

The calibration screen you’re looking at is meant to be a reference for when you adjust your TV’s overscan/underscan/zoom/“just scan” settings directly. The Apple TV simply sends a signal to your TV like any other device, and your TV needs to be set to display that signal at the correct ratio/zoom. This is always adjusted on the TV, not on the source device.

You should be able to fix the problem in your TV’s menu somewhere. It should be in video settings, but sometimes it’s in the quick menu for some reason, or it might be in a settings menu for individual inputs. It’s there somewhere - look for the keywords “overscan, underscan, zoom, or just scan.” “Just Scan” is often the setting you want. Check your manual if you can’t find it. Keep that calibration screen up to verify that you’re choosing the correct setting.

If you really can’t find it, try plugging into a different input to see if it happens to already use the correct setting. Better yet, call LG support.