To learn more, I wholeheartedly recommend the Vulkan tutorial website: https://vulkan-tutorial.com/. The tutorial also covers how to add textures, depth buffers, model loading, and mipmaps. The code for the book is based on this tutorial, so it should be easy to follow and should help you take the Vulkan code base in the book further:
The source code for the Doom 3 Vulkan renderer is available at https://github.com/DustinHLand/vkDOOM3—it is fun to see the code in practice:
I also recommend reading the blog at https://www.fasterthan.life/blog, as it goes through the journey of porting the Doom 3 OpenGL code to Vulkan. In this book, we let Vulkan allocate and deallocate resources. This blog goes into detail about how memory management is done in Vulkan.