Editing iMessages

will it work the other way around though? after i send a message, i blocked the person. then i edited the message. then, just to be sure the edit went through, i unblocked and blocked again. did the edit go through?

You can't see when someone blocks you. You can also still edit the iMessage, even if the recipient has blocked you. However, the change will not happen on the recipient's iPhone, after blocking. Just tested it.

After an iMessage has been sent, you can edit it for up to 15 minutes. After that, the option to edit the message closes. In order for the message to be edited at the recipient, it also requires that the recipient is updated to iOS 16.