caught in the end

I would like that when entering the end and being the portal to return closed one can not respaw in the overworld but be trapped there until killing the ender dragon or if they want to add something in case they lose their items that is a special food or drink that is on the main island or let go of the dragon on its breath, or in whatever way you want to implement it but my point is that the player is doomed like the endermans to be trapped in the end until the dragon dies or they get that special item that returns them (and that the item only works on the main island).