With Autotransitioning, one can transition from sketching a line to sketching a tangent arc, and vice versa, without selecting the arc tool. https://help.solidworks.com/2018/English/SolidWorks/sldworks/t_Autotransitioning.htm
To toggle between line and arc without returning to the endpoint, press A.
I have, long ago, reassigned the keyboard letter A to zoom to fit.
I have searched here...
Where can I find the command for Autotransitioning?