Hi there Rob thanks for reaching out! You can set the standard styling for text or any other shape by making sure you are not selecting any object and then adjusting the font family size or any other shape property in the properties bar at the top of your canvas. Any styling you select while not selecting a specific shape will from that point on be applied to all new shapes dragged onto the canvas. 

You can learn more about text styling in this Help Center article and more about shape styling in this Help Center article. Hope this helps!