Is there a Safari extension that will block certain sites from being accessed?

Now that Safari on iOS can have extensions like an AdBlocker, is there an extension that will block sites from being accessed, like WasteNoTime does on the Mac?

With restrictions on the iPhone, you can only whitelist websites and all other websites will be blocked, but not the other way around. Or you can disable Safari entirely, something I would prefer not having to do.

I currently have WasteNoTime on my Macs, and it works in preventing from being distracted, however, sometimes i find myself using Safari on my iPhone and I'd like to block that as well.