Yes, you can play PUBG on Redmi 6A.
No. Redmi 6A does not come with the earphone in the box. You have to buy it separately.
No. Redmi 6A does not have Dolby Digital sound support.
No. Redmi 6A does not have the gorilla glass protection.
The Redmi 6A is a fairly good update to the Redmi 5A, which itself was barely any different compared to the Redmi 4A. You now get a tall screen, better processor, and improved polish overall.