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Is it possible someone has guessed your Apple ID password and has commandeered your account?
It would then appear as though you sent them.
Random Chinese texts been a common problem in iPhone for almost a decade. If you search the Rogers community forum or the Apple community forum you'll find reasons. Harmless, but annoying, but the texts usually go to contacts; if the messages are going to numbers foreign to you that you've never texted and are not in your contacts, then that's a separate issue. There was an iPhone hack two or three years ago that caused a similar issue to yours. Search around the Apple forum.