Specifically for 1.16 version:
The Kingdom of Hekron modpack aims to improve:
Biomes (7 mods including Oh the Biomes you'll go, Better Nether and Better End)
Structures (10 mods including When Dungeons Arise, Repurposed Structures and Dungeons Enhanced)
Animals and Monsters (17 mods including Ice and Fire: Dragons, Mutant Beasts and Alex's Mobs)
Weapons and Tools (10 mods including Spartan Weaponry, Epic Knights: Shields, Armor and Weapons and Upgraded Netherite)
Dimensions (4 mods including Blue Skies, Atum 2: Return to the Sands and The Undergarden)
and a few other mods to add small tweaks
The Kingdom of Hekron only adds 68 mods to help the Modpack run on worse computers, so only the most important were selected. It has many more popular mods but also includes lesser known mods to make the experience more original. Overall, The Kingdom of Hekron was created to make the experience of Minecraft much more fun by adding lots of new content, especially focused on exploration, while keeping the game to its roots in a vanilla friendly style.