1 new blocks and items were added to Minecraft 1.18 java edition.
Caves and Cliffs - Part 2
An update so big they split it in two. Almost all the blocks and items where added in 1.17. Caves and Cliffs part one technically added most of the blocks and items to be found in 1.18 but they are not found in world until part two. Part two focuses on changes to world gerneration.