GROMACS version: 2022
GROMACS modification: no
Here post your question : Is it possible?
Anything is possible, but first ask why there isn’t one already. AFAIK, there is no well-developed nucleic acid parameter set in OPLS-AA. AMBER is probably the de facto standard these days, though the versions natively supported by GROMACS are ancient and shouldn’t be used. Other groups produce ports for newer parameter sets, though.