1Cor 15:20-22, 20 But now Christ is risen from the dead, and has become the firstfruits of those who have fallen asleep. 21 For since by man came death, by Man also came the resurrection of the dead. For as in Adam all die, even so in Christ all shall be made alive.
This verse is not one of the best for our consideration in arguing for young earth creation but it’s worth observing. The apostle Paul states that by Adam came death. What I wrestle with is this, if creation took a longer duration perhaps millions or billions of years, were there no deaths until Adam sinned? A valid argument could be made that the death mentioned here is that of humans and not of animals or vegetation. Another thing that makes this verse a little weaker to defend my position is the animals that feed on flesh, meaning there would have to be death for them to survive. But the counter argument I would make is that perhaps all animals fed on vegetation just as Adam did in the garden before the fall.
To further look at day 6, the creation of man and land animals, did it take millions or billions of years to make man?, that would not make sense. God created man to have dominion (Gen 1:26) which would suggest that creation was made for man. Furthermore, the Bible says man Adam named the animals which would perfectly fit with the literal day count for that to be possible. And Adam did not name each animal but species (eg. Dog kind not each breed, bird kind not each bird etc). To conclude.