This is already implemented by means of having Ctrl pressed when selecting the depot tile.

Already fixed, closed

Simply because there is a voodoo ceremony that can be invoked each time a player wishes to apply a non-default option doesn't mean that it is desirable to force that method.

Take

Expert Settings>Company>New Orders are non-stop by default

as an instance. This, using the "already fixed" logic above is totally unnecessary as the player could always apply non-stop manually after adding the order.

This suggestion is simply the same thing in blue.

And the purple version is #7777

Holding Ctrl to do a variation of an action is a regular UI convention in OpenTTD, nothing strange about it.