Individual objects as bonds, reaction arrows, graphical objects, text boxes or sets of objects can be scaled.
Select these objects -> corners of a bounding rectangle will appear.
Drag one of the corners - > the selection will be scaled proportionally.
In case of bond scaling, the percentage of the current bond length relative to the default value will be visible.
The same result can be achieved by opening the Format... dialog either through the Edit> Format option or from the pop-up menu.