A special group of decorative blocks are called Carved Wood blocks. They are crafted using a Carving Bench from normal logs, or a knife from stripped logs. If using a knife, one of eight variations of that Carved Wood will be crafted depending on the relative positions of the Knife and stripped log in the crafting grid. Each variation of a Carved Wood has different visual patterns on it but they are all designed to fit together so that you can create nice looking builds.
As of version 1.15.2-2.5.7, all overworld logs have carved wood variations.
These are the carved wood variants for nether stems, namely Crimson Stem and Warped Stem. Differing from their overworld counterparts, these blocks have netherly animations!
You can craft a Carving Bench that will allow you to easily craft carved wood.