The type of structures you will be seeing depends on their rarity and the biome. You can change the spawning rate in the setting of the behavior pack.
Credits: MCZackGaminG

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
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How to install addons:
- Download the addon straight from your device
- Find and open the .mcpack or .mcworld files that you download earlier
- Click on it to start importing into Minecraft Pocket Edition
- Open the game
- Create a new world or edit an existing world
- Scroll down to the Add-ons section and select the ones you want to apply
- Make sure to enable Experimental features in the world's Settings