When someone blocks your text messages, irregardless if they use an iPhone or an Android phone, they have a reason. Instead of trying to bypass the block with some kind of 'hack', you might want to instead contact them using a different communication method to find out why, or if you do know why apologize profusely and sincerely.
Welcome to Android Central! I think RCS chat has read receipts, but iPhones don't support RCS, so that wouldn't work. SMS has delivery receipts, but that won't tell you if it was read.