This issue is being filed as part of PR feedback for flutter/plugins#3325.

That PR adds the missing ability to enable pinch to zoom and on-screen zoom controls for WebViews running on Android. iOS pinch to zoom already works but there isn't currently a way to disable that functionality if a dev wanted to do so.

The available params that control pinch zoom/on-screen zoom controls on Android's WebView and Apple's WKWebView are not one-to-one but it seems the basic functionality of enabling/disabling zoom on a WebView for both platforms should be possible.