Lockdown is a blacklist style “vpn” that is run on your device and will help with ads and tracking when browsing and in games. For YouTube, I go about sideloading uyou plus which covers any ads and similar issues within YouTube itself.
https://apps.apple.com/ca/app/lockdown-privacy-vpn-proxy/id1469783711
A lot of computers people buy from box stores are preloaded and configured to use chrome as the default for many years. Newer prebuilt a May no longer do that, but I doubt it.