I cannot get rid of sex messages on my iPhone 7. I have tried blocking, STOP,

Report spam or junk in the Messages app

You can report iMessages that look like spam or junk from the Messages app. If you get an iMessage from someone who's not saved in your Contacts, you'll see a Report Junk link under the message.

Tap Report Junk, then tap Delete and Report Junk. Messages will forward the sender's information and the message to Apple, as well as delete the message from your device. You can't undo deleting a message.

Reporting junk doesn't block the sender from being able to send another message. If you don't want to receive these messages, you need to block the contact.

Block messages from a specific person or number

To view and manage your list of blocked contacts and phone numbers, go to Settings > Messages > Blocked Contacts. See the Apple Support article Block phone numbers, contacts, and emails on your iPhone, iPad, or iPod touch.

Block, filter, and report messages on iPhone - Apple Support

To report SMS and MMS messages, contact your carrier.