All you need to do is Load the save and use the Ryno to kill some enemies. It will reach level 6. Once it reaches level 6 you will get the trophy. Enjoy
THE SAVE FILE
https://mega.nz/folder/KgtRkZrY#j0TrfuHmA4zD22rAhmsiTw/folder/Gp83Ca5K
THE SAVE FILE
https://mega.nz/folder/KgtRkZrY#j0TrfuHmA4zD22rAhmsiTw/folder/Gp83Ca5K