8D Audio is sound that is made by 8 different channels. This channels change one by one and give you a very mind-blowing sound, but later you see that is perfect to listen.
In other terms, 8D is Ambisonics sound.
Sound comes from 8 different directions on your headphones.
You have to listen to headphones.
Now you can find a lot of videos YouTube that have 8D sound.
You can easily search 8D song, and you will find a lot of them.