What a soft-gel build is for
A builder overlay is a splint. It goes over your own nail, cures hard enough to stop the nail flexing at the stress point, and stays flexible enough to move with the nail rather than snapping away from it. For anyone whose nails peel, split at the sides or bend and tear before they get any length, that combination is the fix.
It is not primarily a length service. You can gain a few millimeters past the free edge, but if you want a dramatic change of length or a tapered shape, acrylic is the right call and we would rather send you there than build something that will not hold. For length on a soft-gel system, Gel X is the option to look at.