Are you talking about an extension app, or a built-in translation feature? I want to translate full web pages in Safari, clicked on the aA in the browser bar and a translation option was there, now not, and I can highlight text to translate, but not the same or easy as that first time was.
built in. Click the Aa button at left of the addr bar, you would see the button to translate(attached a screenshot)
the built in translate renders the web pages quite well. It auto translate the web page if you go to next level of the webpage. However, it only translates the current level of the web page, if some of the web contents are nested, the translate would not render that part of webpage.
in iOS 14, Japanese was supported in Translate App, but not in Web Translate in Safari. In IOs15, both Translate App and Safari are supported.