1 Peter 3:14-15 (HCSB)
14 But even if you should suffer for righteousness, you are blessed. Do not fear what they fear or be disturbed,
15 but honor the Messiah as Lord in your hearts. Always be ready to give a defense to anyone who asks you for a reason for the hope that is in you.
Peter says to "sanctify Christ as Lord in your hearts", which is a reference to Isaiah 8:12-13, which says the same about Yahweh, and therefore, this is an identification of Jesus as Yahweh.
This passage has both a textual variant, and a contested translation. Some manuscripts read "sanctify the Lord God", instead of "sanctify Christ as Lord". Additionally, some translate "sanctify Christ as Lord" as something like, "in your hearts honor Christ the Lord as holy" (ESV, REV, CSB, CEB).
As with other Yahweh texts applied to Jesus by the New Testament authors, it is an over-reading of the text to assert that a Yahweh text cited in reference to Jesus means that Jesus just is Yahweh. The New Testament authors allude to a text, or draw on the same idea, or repurpose it and apply it to Jesus, but none of that is sufficient to assert that Jesus is being declared to actually be Yahweh, because there are too many other ways to understand the passage which do not require that, and are far more likely when considered in light of the rest of the New Testament.
Peter is a competent author. Notice the whole tenor of how he speaks about God and Jesus in this epistle (1 Peter 1:3, 1:21, 2:5, 4:11, 5:10). The assertion that he is suddenly dropping the doctrine that Jesus simply is Yahweh in a passage like the one in question, with no further explanation, makes little sense in light of the context of the epistle as a whole. Further, it is not always the case that the one to whom an Old Testament verse is being applied is the same person from the original verse (e.g. Matthew 2:15 with Hosea 11:1, Matthew 1:23 with Isaiah 7:14-16).