The new product has adopted a new look. Do I need to apply for a separate patent for appearance after applying for a patent for invention?

It depends on whether you need a patent to protect this appearance. If you don't think this new look is very important, you don't need to apply, and it won't affect the use of your invention patent.

If you want to apply for appearance, it has something to do with whether there are drawings in your invention patent. If there are drawings and pictures to fully express this new appearance, it will be unstable to apply for the right of appearance again, and it will be deemed invalid by others.

If there is no picture in the previous invention patent, there is only a text description, which will not affect the application for a patent for appearance.