Please add
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" />
to the <head> area of your website.
Moreover, you can disable pinch to zoom by adding
webView.isMultipleTouchEnabled = false
under this line in WebViewController.swift file: https://prnt.sc/vg0x0v