Mastery is not magic, it's process. - Ryan Kingslien
View the original document above to download the full pdf. Inside you will find a flow chart for working with 3D art for Unreal Engine. The process is similar for Unity, however there may be some alterations such as the render space you use when baking maps (DirectX vs. OpenGL; requires inverting the green channel of the Mikkt normal space map), export/import settings and others.
Knowing what kind of artist you want to be will dictate what areas you concentrate in. While general knowledge of all aspects is expected of most artists, as you gain experience you will find that you specialize further and further in specific areas. For example, a Concept Artist will be the most artistic, having specialized knowledge in traditional and digital art whereas a tech artist will have specialized knowledge in programming, helping the team to create or improve workflow tools and ensure 3D assets look and work their best.
If you are overwhelmed, take smaller bites. - Ryan Kingslein
If you would like to take a look at some popular games and how the environments were created, please go to https://noclip.website/.
Before beginning to learn 3D, you should be aware that it takes a great deal of time to learn your chosen field within 3D. Furthermore, it takes time to refine your processes and become faster so that you can create at a rate comparable to the highest quality game art producers in the world. An example of a AAA timetable for creating a character is below. Given that an artist might work 8 (or more) hours per day, the character below took at least 500 hours to create.