No matter how much costly Chromebook or Pixelbook is, the work process is likely to be the same in all.Though, all of them will not look the same at all. Chrome themes have been there for a long time, and they might not apply to the whole Chrome OS system, but they are ideal for Chrome browser that you use from time to time.
Source: https://customer-support-en.com/how-to-apply-test-theme-in-chromebook/