Why am I getting overscan when i play a game on my ipad and how can I stop it?

I have an iPad Pro 12in. When I play ‘12 labours of Hercules XVI’, there is overscan that prevents me from getting all the points. I only found this out when watching a walkthrough on YouTube and they had way more stuff around the edges of their game! I tried to change the ‘zoom’ in settings but it didn’t not affect what I could see in the game. Any advice on how to stop the overscan would be gratefully received.