Tripod is the best way to get night photos because it provides a steady support for long exposures. But, if you want to go without a full size tripod there are other options.
1) Crank the ISO up so you have a high enough shutter speed to hand hold. Advantage - no additional gear, flexibility in composition. Disadvantage - high noise from the high ISO.
2) Use available support. Find trash cans, tables and railings (if wide enough) to use as a tripod. Advantage - no additional gear, long exposures are possible if you add a cable release or are very careful pressing the shutter release. Disadvantage - limited composition based on location of solid object you're setting the camera on & no ability to tilt the camera up and down.
3) Available support with tabletop tripod and cable release. Advantage - long exposures are possible. Slight advantage in composition with tabletop tripod because you have the ability to tilt the camera up and down easier. Disadvantage - composition is still limited by the location of the solid object you're sitting the tabletop tripod on.
So, using a tripod gives the most flexibility, but other options can be used. Tokyo Disney bans tripods altogether, so all of the nighttime shots you've seen from Tokyo Disneyland or Tokyo Disney Sea were taken using available support.