ESP32 ADC measurment with variable input voltage?

ok, but if the voltage is divided by 2 by the voltage divider, that value needs to de doubled right? So it would be about 5% inaccurate

But how is that technically possible? I can not understand that.
How can it just set something to such a stable voltage without comparing it to anything? Would there not have to be some stable voltage to achieve a steady reference voltage?

good that I chose the S3 then! I did not know that