When you need an iPhone X alternative that is on iOS and is about the same size, the iPhone 8 is your pick. You will give up some of the more advanced camera features and FaceID, but you still get a great phone at a more affordable price.
The iPhone 8 features a True-Tone screen that's about an inch smaller than the iPhone X's and it uses an LCD instead of OLED, but it's still pleasing to look at and it performs well in a lot of light conditions.
Apple packs in the same A11 Bionic processor, you can fast charge and wirelessly charge and the iPhone 8 is easy to put into your pocket or hold with one hand for most users. You get a good rear camera that takes nice photos, though you can't do Portrait mode photos. You also get TouchID, so you can still login without your passcode.
You can buy the iPhone 8 at Apple and from major carriers. Here are the best iPhone 8 deals.