Battery Health dropped to 92% after 259 cycles

If you have an iPhone 14 or earlier, yes, that's normal. Per Apple, batteries of iPhone 14 models and earlier are designed to retain 80 percent of their original capacity at 500 complete charge cycles under ideal conditions. So losing only 8% after more than half that number of cycles is perhaps even a bit better than average. Under normal use, you can expect to lose about 1% of battery health per month.

Regards.

It is normal to expect that the battery will decline about 1% for every 25 charge cycles.

259 cycles divided by 25 = 10.4%, so it would be normal for the battery to be at about 89-90% at this time.

At 92%, your battery is doing better than normal.

Apple will replace the battery in the iPhone 15 if it falls below 80% in the first year. That would be 500 cycles.

Apple claims in the product literature that under "ideal conditions", the iPhone 15 battery may handle up to 1,000 charge cycles, but the disclaimers are lengthy and buried in the small print footnotes.

As far as I can tell, "ideal conditions" would only exist in an ideal world.