As a web developer of a website, I need to check if my site is working without Site Specific Hacks in order to check if a Quirks [1] is still required. [1]: https://github.com/WebKit/WebKit/blob/main/Source/WebCore/page/Quirks.cpp See the discussion in Bug 247445
<rdar://problem/102019360>
This is possible through the Web Inspector on Safari Desktop See https://webkit.org/web-inspector/device-settings/ but not on the device itself.