If the file triggers a jailbreak, you usually cannot open it in Safari directly (as Safari may patch the exploit). Instead, save the file to an app like Documents by Readdle or iCab Mobile and force open it in a UIWebView—a rendering engine removed in iOS 10+.
Because the original jailbreaks.app domain has shifted focus (it now primarily serves a macOS utility), the legacy.html variant survives in three places: jailbreaks.apps legacy.html