An extended world height isn't possible on Minecraft: Bedrock Edition.
#Extended world height!
calm swift
This is a Minecraft: Bedrock Edition limitation.
Heights lower than -512 or higher than 512 in the overworld (and custom dimensions mapped by Geyser to the overworld), and heights lower than 0 or higher than 256 in other dimensions (GeyserMC/Geyser#3804)
For more information on current limitations with Geyser, please see the following wiki page: https://geysermc.org/wiki/geyser/current-limitations