There are several ways to bend harmonics...

1. Bend the strings behind the nut...

2. If you have a floating bridg esystem, or a tune-o-matic system, you can use your palm to push down on the strings, to raise the pitch....

3. With the use of a tremoolo system...

4. With the use of specific pedals...

And 5., Which I suggest you use with extreme caution...
Bend the neck itself, as in hold the headstock and press it into' your own body... This is horrible for the guitar, but if used sparingly, it'll be fine...