Harold B. Lee teaches that the Son can only do what the Father has previously done (John 5:19).
Harold B. Lee, Conference Report (April 1969): 130
True concept of God
I would rather be concerned in an attempt to enlarge his views and his understanding as to the true concept of that glorified being whom all so-called Christians worship as God, our Heavenly Father.
The reasoning of Joseph Smith, in the partial statement from which he has quoted, "that God was once as we are now," is given additional strength if our brother will recall the words of the Master: "The Son can do nothing of himself, but what he seeth the Father do; for what things soever he [the Father] doeth, these also doeth the Son likewise." (John 5:19.)
When we consider the fact that our Lord and Master, Jesus of Nazareth, one of the Godhead, came to tabernacle in mortality, then this quoted statement, taken literally, is of great significance.
The scriptures make it plain to the student of these sacred writings that there are three personages in the Godhead: (1) God, the Eternal Father, also known as the Father of our spirits, (2) his Son, Jesus Christ, the Redeemer, even Jehovah, and (3) the Holy Ghost.
We are told in an inspired explanation that "the Father has a body of flesh and bones as tangible as man's; the Son also; but the Holy Ghost has not a body of flesh and bones, but is a personage of Spirit . . . " (D&C 130:22.)