Why would they do that when the store closes at 9pm. Seems counterproductive if someone is looking for stock to buy between 6pm and 9pm when they get off work.
That's how they have been doing it for launch week. Also any other day, when things die down, Once the clock turns 8 PM, the in-store pick up available changes to next day. You can check this yourself on the iPhone 7 or 8 and you'll see that typically after 8 pm is when it switches to next day store pick up.
I'm pretty sure in a couple of weeks, the XS and XS Max will be back to normal where you can pick it up on the same day if you order before 8 PM.
Edit: Plus I've been monitoring this daily and that's what I have been seeing so far.
[doublepost=1538711183][/doublepost]Also, just because the apple store app or apple.com shows it unavailable for pick up doesn't necessarily mean they are sold out. Even if they disable this at 6 PM, you can still walk to the Apple store and still be able to pick one up.