You can't opt Composition Scheme u/s 10 of the CGST Act 2017 as your Aggregate Turnover exceeds Rs. 1.5 crore.
Hence you have to go for REGULAR SCHEME REGISTRATION. The applicable Rate of GST for Restaurant Services is 5% without the benefit of ITC. Collect 2.5% CGST and 2.5% SGST from your customers and deposit the same with the government exchequer. But note that you will not be able to claim ITC on GST paid on your inward supplies.
Only those Restaurants can charge 18% GST ( 9% CGST & 9% SGST ) with the benefit of ITC, which are located in a Hotel and the Room Tariff per day of the Hotel exceeds Rs. 7,500.