How can I confirm if I'm not blocked when a text says 'Delivered' on an iPhone?

What you can tell, if the text says "Delivered" but the person doesn't respond, is that they are uninterested in replying or currently unable to do so.

As noted previously, there is no way to tell if you've been blocked.

Not necessarily. Just because it shows Delivered doesn't mean you aren't blocked. There could be many reasons for Delivered showing and not showing, such as the recipient's device is out of battery, shut off, no connection etc. There is no definite way to tell if you were blocked.

LondonBrit wrote:

Thank you

You are very welcome. Take care.