I am assembling a portable device such as a smartwatch, what is the best circuit for auto cut off if the device I use is 18650 3.7V, bmp280, mpu6050, esp32 wroom 32 so that it is safe?
First, you can't run an ESP32 from a 18650 battery. The maximum voltage for the ESP32 is 3.6V.
That sounds rather large for a smart watch
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I just looked for the cut off circuit because there is already a step down ams1117 3.3v there, I saw some people use cutoff so that the battery doesn't go straight to 0v so it's safe
The AMS1117 need at least 4.3V on the input in order to regulate. Your battery is only 3.7V so you will never have a 3.3V regulated output.
Post your schematic so we can see what you have so far.
I don't see an AMS1117.
Are you sure you posted the correct schematic?
I changed it with another regulator, I just found out about the cut off before entering the stepdown regulator so that the battery doesn't actually go to 0v
Once the circuit auto powers off, how will you turn it back on?
It shouldn't go even down to 2.5V. To be on safe side set cut off at 2.8V.
Esp32 board with battery management would save you from some headache.
Now I see TWO regulators that don't seem to be connected to anything