I totally agree with the fact that there is no solution as yet from Apple. This is an important issue because many people have vision issues and need the ability to increase and decrease the global font size to view the content of an HTML document being displayed using the WKWebView class. Just like when they are using Safari on their Mac computer they can increase/decrease font size by using ⌘ - or, ⌘ +, having this ability with WKWebView woulds be very important. UIWebView, which is being deprecated, has this ability. I hope Apple comes up with a new release that fixes this problem.