Hi and thank you for your interesting post.
I want to measure the current consumption on RPi3 using a UNI-T UT61E True RMS multimeter. Is it possible to do that without utilizing any other devices? I'd be thankful if you answer my question.
I can only go by the spec and picture on Amazon. The meter by itself appears to be capable of measuring DC current to 10A. Of course you will need to put the meter in series between the PSU and the Pi, so you may need to make or modify a USB lead, if that is how your Pi is supplied.