There are two different concepts: UIKit size and Native resolution.
UIKit size is represented by points and is used when you're positioning views inside your project. Let's say your screen is has size 414x896 points, and you center your view to position [207,448], your view will be in the center of the screen.
Native resolution is represented by pixels and it's telling how much pixels screen of the device has. You can get native resolution of device by multiplying UIKit size with Native Scale factor which is individual for each device.
I created table for these sizes, sclae factors and resolution for all iPhones which supports iOS 12
iPhone | UIKit size (points) | Native resolution (pixels) | Native Scale factor
-------------|---------------------|----------------------------|--------------------
Xs Max | 414x896 | 1242x2688 | 3
X, Xs | 375x812 | 1125x2436 | 3
Xr | 414x896 | 828x1792 | 2
6+,6s+,7+,8+ | 414x736 | 1080x1920 | 2.608
6,6s,7,8 | 375x667 | 750x1334 | 2
5s,SE | 320x568 | 640x1136 | 2
... from this table you can see that your iPhone Xr has UIKit size 414x896, not 375x812 as your wrote in your question.
You can get device's UIKit size by getting screen's bounds
UIScreen.main.bounds
and native resolution by getting native bounds
UIScreen.main.nativeBounds
... each of these works well for iPhone Xr so check once again if you're running your code on iPhone Xr and not on iPhone Xs/X which has UIKit size 375x812. Also this 750x1624 is just some weird scale of Xr' native resolution, so check if you're not doing any extra math.