You’re probably already aware that you can enter bulleted or numbered lists in Google Docs using the appropriate buttons on the toolbar (there’s a post about customising them here):
In line with how many other word processing programs function, Google Docs, Slides, and Drawings will now automatically turn on the relevant list mode when the application detects that you want to make a bulleted or numbered list, based on what first character you enter in your paragraph.
For example, if the first visible character is an asterisk * or hyphen – followed by a space, a bulleted list will be assumed.
So if I type this:
Docs will assume I want a bullet list:
Similarly, entering 1) or a. followed by a space begins a numbered list, as would similar character permutations such as (A):
This feature is switched on by default, but you can disable it from the menu using Tools > Preferences. To back out of an automatically-entered list mode, just press backspace immediately after list mode has been launched, to revert to whatever plain-text characters (asterisk followed by space etc.) caused the list mode to launch.