Hello @Kejan.
Both these mounts, along with other rare mounts and cosmetics, can be obtained through PvP Chests.
These chests are obtained by winning not Ranked and Random PvP matches. You earn x1 Chest for your first daily win on each mode, and then x1 Chest for every 2 Ranked wins (every 4 wins on Random battles).
Keep in mind these mounts and cosmetics are totally random and quite rare.
Let me know if you have further questions.