Today's Minecraft: Java Edition update includes the second part of Minecraft's Caves and Cliffs update. Players who travel a lot, regardless of whether they're in an old world or a newly-generated one, will notice the changes quickly.
Their dimensions and generation height layers have been changed, in addition to the fundamentally changing how caves and mountains create. The increase in the build height limit for mountains and the loosening of restrictions on generation for game worlds has allowed peaks to reach Y=256. The increased height makes mountain peaks more treacherous and jagged.
The 1.18 update not only increased the generation height in Minecraft but also changed the way that biomes work around and atop mountains. Three biomes can be found on mountain slopes: meadows and groves as well as snowy areas. Mountain peaks can also have jagged, frozen and stony biomes to increase the variety of their massive natural structures.
The Minecraft biomes will all be found on mountains and will be rich in biodiversity. This is a significant improvement on the original capabilities of mountains, which were essentially limited to holding ore and stone. The Wild Update to Minecraft is due to release in 2022. This means that there will likely be more improvements to the Overworld's wild reaches. Mojang is ready to take on this challenge.
Players who are transitioning to Minecraft 1.18 should not expect dramatic changes in the mountains near their positions. However, they will notice some of the most noticeable changes after a bit of exploration. The block types and depth of underground layers have changed. Caves can now be found in a variety of sizes and have extremely small spaces. Mountains look grander and have more life than ever before. This is due to the implementation of biomes.
Caves & Cliffs Part 2 is truly a game changer in Minecraft's world generation. The best way to see it is to open your Minecraft server or world and have a look yourself.