Netflix is a cloud-based service. Movie files and user permissions are stored on Netflix’s servers, not inside the app. A modified app cannot "force" the server to send 4K data if there isn't a valid, high-tier subscription attached to the login.
In many regions, Netflix offers a "Mobile-only" plan at a significantly lower price point. Netflix MOD APK v8.54.0 (4k Premium Unlocked, No Ads)
Avoid downloading files labeled "Netflix MOD APK" from unverified websites, as the risk of compromising your phone's security is significantly higher than the likelihood of getting free 4K streaming. Netflix is a cloud-based service