A 27" sink will undermount into a 27" cabinet. A 33" sink will undermount into a 33" cabinet, etc. I've done this a million times.
The sink manufacturers provide junk clips and want to provide access to fat plumber hands. Strap your sink in place, Hercules Universal Sink Harness (Braxton Bragg) or Sink Strap (GranQuartz), no access needed and your sink won't leak.
Oh, and drilling into your engineered stone for the clips voids the manufacturer's warranty, so don't have your sink clipped in place by the fabricator before installation please. And he needs room for the clips along the front so you'll get an ugly fat front rail. Skinny rail with straps:
2 1/4" with a 1 3/8" overhang with straps. Purty,
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Simple and individual shelves
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