Does a factory reset also delete the eSim?

Depends on how you do it.

If using the Reset option in the iPhone settings you will be given the option of retaining the eSim or deleting it.

If you restore using iTunes or Finder on a computer, then it will delete the eSim from the iPhone.

What I meant was if you reset / wipe the iPhone on a computer it will delete the eSim.

If you restore a backup from the computer after the iPhone has been wiped, but you retained the eSim it will keep it after the datas is restored to the iPhone.