Minecraft wiki entry for Exit_portal, associated text: In Bedrock Edition, if the player manages to break all of the end portal blocks in the exit portal, the entire structure regenerates after 5 seconds.
If all of the portal blocks have end crystals above (so the fire constantly eliminates the portal), this regeneration process repeats until a portal block successfully regenerates.
If an End Portal is built in Creative mode in The End or generated through custom world generation, then it also acts as an Exit Portal.
If the exit portal generates at the tallest possible height and the ender dragon is defeated, the portal blocks generate in the exit portal as normal, but the dragon egg does not spawn due to its intended location surpassing the build height limit.
It is possible For End portals to not generate at all. If no blocks generates below x=0, z=0, The end portal would fail to generate due to it being cut by the void, with the only thing that generates is the small pillar.
In Bedrock Edition, if there are other end portal blocks in the End and the exit portal structure is completely destroyed, it does not regenerate until the other end portal blocks are removed.