Yes, definitely some magic happening here: http://opencircuitdesign.com/magic/tutorials/tut8.html

The extractor computes from the layout the information needed to run simulation tools such as crystal (1) and esim (1). This information includes the sizes and shapes of transistors, and the connectivity, resistance, and parasitic capacitance of nodes. Both capacitance to substrate and several kinds of internodal coupling capacitances are extracted.

@SimonM depending on how complex the projects you are after are, you could try this approach to get something from magic to simulate with SPICE maybe? Not 100% sure that'd this would be the way to go but..

Don't confuse "esim" in the magc tutorial with "eSim" in the link you posted. They are completely different things. Magic's ".sim" format is only understood by IRSIM (although IRSIM is a very useful simulator; it is faster/less accurate than a SPICE simulator (because it treats transistors as resistive switches) but slower than a verilog simulator (because it simulates at the transistor level rather than the gate level). Xschem is not mandatory to run simulations. But for most analog designs, a schematic will be easier to deal with than a hand-written SPICE netlist. If you have any tool that will produce a valid SPICE netlist for the PDK, then that is sufficient for simulation. However, relatively few schematic editors currently have a setup for the sky130 open PDK. Xschem is the most commonly used schematic editor that does have a setup for sky130.

Thank you for the disambiguation!