When looking at people who receive new names, it is easy to see when referring to the flesh, the old name is used, but when referring to the promise the new name is used. This is most apparent when referring to the children of Jacob vs those of Israel. This observation is not the subject of the question, but is the assumed foundation for it.
Sarai is the name used for the woman of the flesh and Sarah used for the woman of the promise.
1 Peter 3:1-6 only alludes to the unblessed שָׂרַ֣י Sarai but neglects to mention the blessed שָׂרָ֖ה Sarah's characteristics. Genesis 18:12-15 shows her outspoken nature, though it was ill-informed. Genesis 21:10-12 shows a cruel nature but God commands Avraham to obey his outspoken wife : "whatever Sarah tells you, hearken to her voice" ( כֹּל֩ אֲשֶׁ֨ר תֹּאמַ֥ר אֵלֶ֛יךָ שָׂרָ֖ה שְׁמַ֣ע בְּקֹלָ֑הּ ) , since he plans to bless both boys as is seen later in the narrative.
Why would 1 Peter 3:1-6 only inform women to behave like שָׂרַ֣י Sarai (the flesh), but not the blessed שָׂרָ֖ה Sarah (who was no longer silent regarding her husband's judgement concerning his children)? Shouldn't the woman of the promise be the model?
1 Peter 3:1-6 [NKJV]
Wives, likewise, be submissive to your own husbands, that even if some do not obey the word, they, without a word, may be won by the conduct of their wives, 2 when they observe your chaste conduct accompanied by fear. 3 Do not let your adornment be merely outward—arranging the hair, wearing gold, or putting on fine apparel— 4 rather let it be the hidden person of the heart, with the incorruptible beauty of a gentle and quiet spirit, which is very precious in the sight of God. 5 For in this manner, in former times, the holy women who trusted in God also adorned themselves, being submissive to their own husbands, 6 as Sarah obeyed Abraham, calling him lord
1 Peter 3 tells nothing else of שָׂרָ֖ה Sarah. This seems to be intentionally misrepresenting our Matriarch & God's command to Avraham in Genesis 21:12.