Is there a 3.3V and 12V 18650 circuit? Is there an all in one circuit which regulates charging, protects and steps up/down an 18650 battery to 12V and 3.3V at the same time, so I can power a sensor and my ESP32?
I would suggest using a 12V controller, and then adding a 3.3V switching regulator using the 12V supply. That would be 2 off-the shelf components and you're done.