If I am in The End, can I create another portal to get out?

I am in creative mode, so dying is not an option. And I don't want to kill the Ender Dragon.

If you're in creative mode, you can easily create another portal in the end to get out.

Or alternatively, you can jump to the void to kill yourself.

If you're on PC, you can also use this command to kill the Ender Dragon easily (if you have cheats enabled/have OP):

/kill @e[type=EnderDragon]

You can kill yourself in creative mode by using this simple command: /kill, or falling into the void. If you want to generate a portal at where you are, run this command: /summon EnderDragon ~ ~ ~ {HealF:0}. Ender dragon will immediately start to die and generate new portal.

Even though you are in creative mode, you can still die to void damage. Jump off the End Island into the void and you will die, and spawn in the overworld.

Use this command:

/setblock x y z minecraft:end_portal

Then you can make a portal block. Go though it, can bring you back to the overworld.

You can use a command block with a delay circuit to remove the portal block and the command block after you go back to the overworld.