I just wrote this in another thread. No need for Photoshop or any other image editor; you can do it all on your iPhone. If you want to reduce the file size of the end image, you can text or email it to yourself or use another app. Right, it's about aspect ratio, not image size. Here's the tricky part, though: with an image like your flag example, Photos wants to crop it in landscape mode -- wider than its height -- unless you force it to "think" in portrait mode. Use the Crop box first to select a portrait-like area -- tall and narrow -- then tap the aspect icon and select 4:5. It will think that you want it to stay tall, and it'll give you a crop boundary to suit (technically 5:4). First, this is what happens with a landscape pic and choosing the 4:5 crop straight away: View attachment 584476 Instead, first, manually select a crop boundary that's taller: View attachment 584477 …which gives you this: View attachment 584478 Then tap the aspect ratio icon, select "4:5" in the pop up sheet, and you get this: View attachment 584479 Hit Done, and you're set. Perfect size for the Watch.