Will my iPhone tell the person I read his text?

I got a text and read it and remembered that my read receipts were off so I know it'd still say delivered on his phone.

After I read the text, I went to go turn on my read receipts.

Will it change right away from delivered to read even though I changed the settings after or will it still say delivered for him since I read it before I changed it?

If you change your read receipts, it'll change to read instead of delivered. Not a good idea lol.