If you want to completely get rid of read receipts, for all your contacts across the Messages app, here’s what you need to do.
First, go to Settings. Then scroll down until you find the Messages section. From there, you want to find a setting that says Send Read Receipts and toggle it off. This will ensure that when your contacts send you a message, they won’t get a read receipt when you open a message from them. This process is device-specific, so if you want to turn off read receipts in all your devices you will have to repeat this process in each individual device and toggle off read receipts in all of them.
This will turn off read receipts for all your messages, but you can also do this for individual contacts instead if you want to make sure some people get updates when you see their messages.