The Wall of Flesh is much much stronger than Skeletron.
You’ll want to use a very strong bow or the demon scythe.
With some healing potions.
Try to stay far away from the WoF and The Hungry (his guards) while attacking.
You’ll also want the rocket or spectre boots and/or some wings.
It will take many tries but eventually you’ll defeat him.
Hope this helps 🙂