Can you stop marketing messages on an iPhone X (e-sim)
Sounds like you are posting about Flash messages.  Depending on the carrier there may be a code that you can enter to disable them, you would need to contact them or their support for help with this.  

You can also check the device settings.  Settings>Phone>Sim Applications (you may or may not have this menu option depending on your carrier).  From there you may have many entries that you can select on the choose to start/stop or deactivate.  See this link for screen shots and more information.