My XR shows 99% after almost 11 months of usage. When plugging into Coconut Battery, it still shows 100%. Much better than my 8 Plus was prior after a year. Should have another solid year of battery life from the XR.
I question the accuracy of the feature as my XS is showing 100% after ten months of ownership.
I suppose it’s possible it hasn’t degraded at all as I’m a fairly light user but my X I used before this phone was down to 88% when I traded it in after the same length of time.