Telephoto Images - iPhoneSE 2020

Do I understand correctly that using the 'zoom' feature to capture an image with my iPhoneSE 2020 results in an image based on fewer pixels, i.e., the image is degraded?

I use an Otterbox Defender case to protect my phone. Are there auxiliary telephoto lenses I can use without removing the camera from the case?

Also, why did the text message with the confirmation code come to my iPhone5, a device without a SIM card? I keep it around so I can save hearing aid batteries when I want to stream the news while doing manual tasks.

thanks

baumgrenze