Zaeks 1
There are a lot of dungeons.
New Dimensions: Atum 2 / Aether / Twilight Forest
There are a lot of new cave biomes
¿1.12.2? New content from 1.13 to 1.21
1.14 villagers, villages and illagers in 1.12.2.
There are a lot of bosses (more than 2)
New ores, armors and weapons (there are more than 5 overworld new ores)
Nether Update in 1.12.2: new biomes, dungeons, mobs... (more content than in 1.16)
New nether ores (there are more than 6 nether ores)
End Update: New ores, generation, structures... (there are more than 2 end ores)
Shields of all materials, backpacks, combine the armor with the elytra, mine the end portal and many more things
New mobs: animals, dragons, blocklings and many more
New decoration: blocks, furniture, doors, windows, roofs, paths, bridges...
Tech: Elevators, security craft, new hoppers...
There are a lot of new biomes
Ocean Update: New ocean generation, dungeons, mobs, armors...