I have discussed the salvific efficacy of water baptism many times on this blog. One can search for these articles, which include, among many others, the following:
Baptism, Salvation, and the New Testament: John 3:1-7
John Greer vs. the biblical doctrine of baptismal regeneration
John Greer vs. the biblical doctrine of baptismal regeneration
While pursuing a work that is a compilation of sundry talks and sermons by Boyd K Packer (1924-2015), one finds, even in passing, references to such a doctrine, including:
You Can become Clean
I am sure that within the sound of my voice there is more than one young person who already has fallen into transgression. Some of you young people, I am sure, almost innocent of any intent but persuaded by the enticements and the temptations, already have misused this power.
Know then, my young friends, that there is a great cleansing power. And know that you can be clean.
If you are outside the Church the covenant of baptism itself represents, among other things, a washing and a cleansing. (Boyd K. Packer, “Why Stay Morally Clean” in “That All May be Edified”: Talks, Sermons and commentary by Boyd K. Packer [Salt Lake City: Bookcraft, 1998], 183)
Elsewhere, in a talk entitled “Someone Up There Loves You,” Packer again affirms baptismal regeneration:
Belief in the Resurrection
You believe in the Resurrection. You must know that baptism for someone who is dead is quite as essential as baptism for someone who is living. There is no difference in the importance of it. One by one it must happen. They must do it here, or it must be done for them here.
The whole New Testament centers on the resurrection of the Lord. The Message is that all are resurrected. Every scripture and every motivation that applies to missionary work has its application to ordinance work for the dead. (Ibid., 300, italics in original)