Unfitered_html is a role capability which admins and editors already have. It can be granted to authors if you trust them to not introduce malicious code. Simply entering code view in the block editor or text mode in the classic editor will allow you to enter any HTML you like on any page if your user has this capability. Even without the capability, code/text view will allow the most common HTML.
In the Classic Editor when I click “Text”, preview shows the HTML tags as text. When I click on “Text” again, same result. That is, my HTML tags are treated as text and not interpreted as HTML tags. In the CyberSecurity SIG Automobile Security the page is opened and the HTML tags are interpreted. In the Cookbooks the HTML tags appear as text.
Is there something other than clicking “Text” that Ii need to do?
unfiltered_html seems to need admin approval so I can’t use it.
Both tabs are merely views of the same content. One allows you to see the HTML code and the other to see the rendered page. The reason the HTML in your linked page appears as text is all the < and > chars have been converted to HTML entities like < and >. When that is done, the browser renders the referenced char as text and does not process the HTML tag.
It’s not clear how it got that way. It most likely got copy and pasted that way from the original source. Either that or some sort of filter is active that is inappropriately converting all text to HTML entities. Try copying the output from your browser and pasting it into a new page using the text tab. I think when that is published it’ll render correctly. If so, you can paste the same back to the original page, using the text view again.
Even without unfiltered_html capability, you can use most formatting HTML, links, images, etc. You are prevented from using riskier things like iframes and scripts.