I find this method is more accurate for me than 3D Touch, so I actually do this instead on my iPhone 7 Plus. Basically, it takes a split second to trigger 3D Touch, and in that period of time I could have long-pressed the spacebar. The latter is very reliable for me, but the former doesn’t trigger as reliably.
I tried it on my old iPhone 8. But it doesn't work that great there, since the spacebar is at the very bottom of the square screen, and therefore there is no further space for scrolling down from there.
On my new iPhone XR it's far more convenient to use, since the spacebar is not at the bottom, and scrolling down (e.g. in order to edit a message) works more reliable.
It still doesn't feel as good as 3d touch on the old thing, e.g. it sometimes doesn't go into touchpad mode when pressed directly after a word and doesn't feel as precise. But it's good enough that I don't terrible miss it.
Earlier poster is correct about not being intuitive. Now that I know about it, that's awesome. Sadly, it's not supported by the Google keyboard (long press kicks off voice search).
It is the natural and best way to do so. You press hard and the cursor moves freely like a mouse pointer, put it where it should be and release. Along with haptic feedback, it's a must have once you start using it. Really beats the magnifying glass method.
An interesting fact is that it's actually a Post 3D touch feature. It should have been possible to do it all the years. But the feature only had been introduced with iOS 12, after the first phone without 3d touch (iPhone Xr) after some years had been released.
I would have been useful for devices like the iPhone SE too.
