Provide a detailed and clear description of feature or change that you want to offer.
in the config you can set I:MaxSoulCrystalLoss=10 to allow permadeath. when you perma die it basically bans players from servers. a option to change this to spectator mode would be nice.

Describe why you want this. If there's a reason.
with spectator mode you can still view the world. and if in multiplayer share information. one mod I know of even adds a hardcore revive mechanic (spectrum has a recipe that is a player head + totem of undying + enchanted golden apple to revive a player who died in hardcore mode)

(I mentioned spectrum even though it is a fabric mod since it works with connector and is in a modpack I play that also contains enigmatic legacy)