score:6
This should be no problem. Terminal 1-3 are connected via link bridges to Jewel so the only thing to consider is how early your check-in opens, this might be only 2 hours before the flight. If you are travelling from terminal 4, this will be harder, as you will have to take a bus there and back.
Alternatively, depending on your airline, you might be able to do an early check-in directly at Jewel. The website of the airport has a long list of airlines which offer early check in at Jewel up to 3 hours before the flight.