Power draw in usage vs battery capacity?
I've never really looked at it like that, but I guess we should take the least generous values from both:
Pure Capacity:
iPhone XR: 2,942 mAh
iPhone SE: 1,624 mAh
Draw:
iPhone XR: "Up to 15 hours", so 196,134 mAh of draw if we take the best case for the iPhone XR.
iPhone SE: 12-13 Hrs on Internet (so, LTE, according to apple) that's roughly 129,92 mAh
; while the capacities are wildly different I don't see the SE being so far behind.
If you can get real power draw numbers you can make your own conclusion. I suspect Apple expects a certain about of idle time (which has been optimised for on the later generations).