The baking process is the same for all PBR materials in Blender.

• Texture Baking for beginners
• Bake multiple materials to one texture map

NOTE: Baking is really slow in Blender. To speed things up, follow these steps:

1. Make sure that all unwrapped UVs are inside the UV Editor area and the UVs aren't overlapping with each other.
2. Change the Resolution of the Render image to the image size you created earlier. (1024x1024, 2048x2048 etc.) Change the 'Tiles X and Y' size under 'Render Properties' tab > Performance to those exact values again. This would result in about 17x faster baking!
3. Furthermore, Cycles uses the number of render samples for baking, which defaults at 64. For baking purposes, it makes sense to reduce it greatly. Try something like 16 samples or even lower, that should be fine.