You can do it right from the iPhone. Go to Settings, Accessibility, Touch, Turn on AssistiveTouch and choose Analytics for Single-Tap. Press the AssistiveTouch button on your screen and it will start gathering analytics. Once it’s done go to Privacy & Security, Analytics & Improvements, Analytics Data and you should see a file at the bottom beginning with sysdiagnose, click on it and save it to your Files. Go into the Files app and click on sysdiagnose, next ioreg, IODeviceTree, now search for raw-panel. It will give you a serial number for your iPhone’s panel but all you need is the first 3 letters to tell if you have a Samsung or LG.