If someone says something close / similar to what it is that you want to convey, use that as a springboard to give your actual opinion.
“Blah blah blah”
You: “I agree with that. I think you’re absolutely right. [insert your opinion here]. It’s exactly like what you said, [repeat whatever they said].
People generally won’t disagree with you, even though you added on to their opinion. Humans enjoy it when others agree with them.
Sometimes it works even if what the other person said is nothing close to what you want them to believe (especially if the other person is… shall we say… not so bright). The natural human desire to have someone agree with their opinions is really that strong.