Audio and video sharing / casting restrictions or disabling it altogether?

My nephew has an iPhone. I have decent TVs and decent sound system. Every time my sister brings him to visit he shares baby shark or whatever he is currently watching around the house. Bar turning everything off (it’s a nuisance to do this when I want to use it myself a lot and it’s a fiddle to do it on multiple devices)... where is the option or feature on my phone and iPad to turn this off?

I want to completely disable any ability to share or cast from the client side phone.