"It may be here said, We have instances wherein God hath not fulfilled his threatenings; as his threatening to Adam, and in him to mankind, that they should surely die, if they should eat the forbidden fruit. I answer, it is not true that God did not fulfil that threatening: he fulfilled it, and will fulfil it in every jot and tittle. When God said, 74 “Thou shalt surely die,” if we respect spiritual death, it was fulfilled in Adam’s person in the day that he ate. For immediately his image, his holy spirit, and original righteousness, which was the highest and best life of our first parents, were lost; and they were immediately in a doleful state of spiritual death.

If we respect temporal death, that was also fulfilled: he brought death upon himself and all his posterity, and he ... suffered [the beginning of] that death on that very day on which he ate. His body was brought into a corruptible, mortal, and dying condition, and so it continued till it was dissolved. If we look at all that death which was comprehended in the threatening, it was, properly speaking, fulfilled in Christ. When God said to Adam, If thou eatest, thou shalt die, he spake not only to him, and of him personally; but the words respected mankind, Adam and his race, and doubtless were so understood by him. His offspring were to be looked upon as sinning in him, and so should die with him. The words do as justly allow of an imputation of death as of sin; they are as well consistent with dying in a surety, as with sinning in one. Therefore, the threatening is fulfilled in the death of Christ, the surety.

https://ccel.org/ccel/edwards/works2/works2.iv.xii.html