You might start with the now quite old but groundbreaking book “Introduction to VLSI design” by Mead and Conway. It shows the chip layouts for basic switches, gates, and stuff like that, and design tools for building circuits up from those. Now imagine decades of improvements to the design tools. For the past few decades chip designs have looked like software programs, except highly parallel. The two main languages (“HDL’s”) are Verilog (looks like C) and VHDL (looks like Ada). You say what circuits you want and how they should be connected, and the compiler and layout software figure out how to place thst stuff on the chip. You can drop “macros” for very complex subsystems into your design, such as communication ports or even microprocessor cores, without having to worry about the insides of the macro blocks. There is a significant FOSS ecosystem of such macros too: see opencores.org for some of what’s available. It’s sort of like Github but for hardware.