This is a little different ( i think !) than playing harmonics
You pluck with the right hands finger
but your right thumb touches the string near where you are plucking ( obviously - the thumb and other fingers are all connected !! )
anyway you can coax all sorts of harmonics by doing this
can you show a video at a master of this technique ?
i seem to think playing bluesy lines work well with these harmonics
all sorts of pitches become available. thanks to the edge of the right thumb lying on the same string being plucked by other finger(s) of the right hand !
I refer to these as "pinch harmonics". It's exactly the same concept as those squealing dive bomb pinch harmonics played by metal guitarists, just deployed differently. In fact, if you throw some string bends or vibrato in and kick on some gnarly distortion or fuzz, I'm willing to bet you could get in that neighborhood-- though using a pick helps a lot. I find them really satisfying, so my fingers like to tend toward doing them if I have distortion or fuzz on.
I'm aware that more proper terminology includes "false harmonics" or "artificial" harmonics, but I don't really like the rationales for using either term. "Pinch" harmonic at least describes the technique you use to produce them, both fingerstyle and with a pick.
If you want a cool harmonic-related trick, play a bassline low on the fretboard while plucking the string exactly 12 frets above. So if you fretted the G on the third fret of the E string, pluck the string right above the 15th fret, and so on. When you do this, it sounds primarily the low harmonics-- I believe the fundamental and the second/+8ve, but I've never checked on a spectrum analyzer or anything. Michael League taught this trick as a way to imitate the sound of an octaver pedal.
He called it a proper sub-octave, but I don't think that's what it is.
Most people are aware that plucking closer to the neck results in a tone with more low end, but plucking exactly in the middle of the string (which is 12 frets up, regardless of whether it's open or stopped) gets you the extreme version of that. Obviously this is easier to do lower on the fretboard, because if you go high up, you run out of fretboard to use as a visual aid.