Yes, you can visit Jewel Changi Airport during a transit, but you must legally clear immigration to enter Singapore, as Jewel is located in the public (landside) area. For a stress-free visit, it is recommended to have a layover of at least five hours. Most travelers from Western countries do not need a visa, but you must complete the digital SG Arrival Card within three days of arrival. If you have a shorter layover and don't want to leave the transit area, you can take the Skytrain between Terminals 2 and 3, which passes directly through the Jewel complex, offering a brief but spectacular view of the HSBC Rain Vortex. Once finished at Jewel, you simply clear departure immigration again using your connecting boarding pass to return to your gate.