Won’t comment on the accuracy, as I’m assuming he’s referencing the generic Mandalorian race, rather than ‘The Mandalorian’.
Regarding @Disaparrel’s comment, to make it smooth, enable Smooth Shading under the Object tab, or search for it using the F3 menu. (SPACE for former 2.79b users)
You’ll then want to add an Edge Split modifer to preserve your sharp edges. Smooth does not mean high poly; I exemplify this as an aside in a former post of mine.
Likewise, it appears you made the dome of the helmet from hand using extrusions. I’d recommend remaking that topology with proportional editing so you can have the desired continuous curve that you appear to be missing out on currently. Nonetheless however, Smooth Shading will help hide those sins.
