A drop in battery health of 1% per month is considered normal. One thing you can count on is your battery health to continue to decline. And it's not linear. It may drop a point or two, then not drop for a few months. But drop it will do.
Do make sure you are charging your phone at night every night, all night long. Do make sure you have optimized battery charging turned on in Settings > Battery > Battery Health. And don't obsess over something which is normal and expected. If by some very odd chance, your battery health dips to 80% in the first 12 months of ownership, Apple will replace the battery under warranty. That is not likely at all.
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