More Structures Command Block 1.12.2, 1.11.2 adds 7 structures (4 in the overworld, 2 in the nether and 1 in the end). You can change the structures to whatever you want. Some include random loot and mobs.
Screenshots:
How to install:
More Structures Command Block 1.12.2, 1.11.2 Download Links
For Minecraft 1.10.2
1st Command: Download from Server 1 – Download from Server 2
2nd Command: Download from Server 1 – Download from Server 2
For Minecraft 1.11.2, 1.11
1st Command: Download from Server 1 – Download from Server 2
2nd Command: Download from Server 1 – Download from Server 2
For Minecraft 1.12.2, 1.12.1, 1.12
1st Command: Download from Server 1 – Download from Server 2
2nd Command: Download from Server 1 – Download from Server 2