As far as I'm aware, custom named styles (like "Normal text" etc.) are not yet supported and nobody is aware of any plans to implement them.
However, implicit, "by example" styles exist and can be used with decent efficiency via "Copy format", "Paste format", "Paint format" and "Select all matching text" functions.
The usage is roughly like this:
- In order to create an implicit style, select an unmarked text passage and tune its properties. Adjust font style, weight, size, color etc.
- In order to use an implicit style, step on marked up text, and do a "Copy format" by pressing Alt+Ctrl+C. Then, select an unmarked text passage and do a "Paste format" by pressing Alt+Ctrl+V.
- Alternatively you can use the "Paint format" icon on the toolbar.
- In order to adjust an existing implicit style, right-click on a styled text passage and click "Select all matching text" in the pull-down menu. Then adjust font style, weight, size, color etc.
WARNING! 99% of Earth population are yet unaware of this due to Google's stup^H^H^H^Hinformation policy. The majority of us earthlings still believe that Google Docs hasn't got text styles and thus sucks.