An overall style can be created for your publication under the Style tab in Project Settings.
Styles applied here will indicate which fonts and colors should be used when a new element is added to the Canvas.
Styles applied here will also apply to any pre-existing elements in the publication which are using default styles (meaning they haven’t had their style edited using the Properties panel).
Please note that styles might not necessarily apply to elements which have been added as part of a block.
Studio also offers the option of saving a set of default styles, which can be used across projects. Click here to find out more about creating default styles.