First, I must say that larabel projects is required very rarely, it's not a cms, if a serious redesign, in any case, rather to the old you will not return. If he uses git, you can always revert to the old design. But again, changing the design and most likely some functionality will change, too, and this functionality will not be compatible with the old theme.
Secondly.. if you still need to do it (the only option when you really need to see something like this: day one the theme of the night is different. Something like this), just in the config file, make the corresponding key in the base controller from which inherit all the others make the method view, which already define the full path to the view function with the theme. Or doing an trait, in which again a method create. That's all