You can use this as an example "# opt ccsd(t,full)/aug-cc-pvtz" or "# opt ccsd(t)/aug-cc-pvdz".

Keep in mind that CCSD calculations are computationally expensive. for small molecule you can use opt keyword also but for large molecule, I advice to use DFT for optimization. Then do single point CCSD calculation.

Basis set you can choose whatever you want but CCSD gives better result if you use "correlation-consistant" type of basis set (eg. aug-cc-pvdz or tz). But aug-ccpvtz or dz use more time than other type of triple zeta basis set.

Hoping it will help you.

# CCSD(T)/6-311+g(d,p) opt freq