On Capacities Desktop, one can use Shift+Enter to create a newline inside of a block, without spawning a new block underneath. There appears to be no equivalent on mobile, but sometimes a single newline character is desired.

One suggested implementation of this could be to implement a setting that allows the user to select whether a new line or new block is the default action on pressing enter, and then make Shift+Enter perform the other non-default action, with an additional toolbar button for mobile devices.