Is there a provision for a person to get himself voluntarily registered though he may not be liable to pay GST

Yes. In terms of section 25 (3) of the CGST Act, a person, though not liable to be registered under Section 22 or Section 24, may get himself registered voluntarily, and all provisions of this Act, as are applicable to a registered taxable person, shall apply to such person.

(ICAI FAQ PUBLICATIONS 06-09-2017 REGISTRATION: FAQ NO. 6)