May I just say for those of us who understand syntax and understand the importance of being exact, there is a HUGE difference between looking for:
Customizer > Layout > Block –>
Customizer > Layout > Blog which is where this actually lives!
So for others who may be struggling looking for this feature, your welcome. Look for the BLOG settings! And by the way, this is my favorite forever theme! I teach this at my local university. What you all have created is beyond brilliant. Thank you. Please never stop developing.