In a new trailer shared by Bandai Namco, it is revealed that in Digimon Story: Alien Time, players will be able to "digital ride" with their partners throughout the digital world.

More importantly, the feature does not seem to be limited to specific Digimon, and players can ride on a variety of available modes of transportation, including Digimon's back, shoulders, wheels, or in the cockpit.

Riding system PV:

Nevertheless, although not fully confirmed, the feature seems to require at least one minimum body size requirement to be used.In other words, you shouldn't be able to ride on the back of Agumon until it actually evolves.