How to change the number of rings on my iPhone 8plus before voicemail picks up

Voice mail is entirely provided by your carrier. Your iPhone does not send the unanswered call to voicemail by itself. It is your carrier that forwards the call to voicemail when it is not answered.

Contact your carrier or consult their web page for information about how to change the duration before calls are transferred to voicemail.

I have never come across any such option on an iPhone.

Apple Inc says; "We read all feedback carefully, but we are unable to respond to each submission individually."

Here is how for iPhone · Country or region* Select your country or region. · Feedback Type* Select feedback type. · Comments* Enter a comment.

Feedback - iPhone - Apple

My IPhone 11 only rings once then goes to voice. I need to change to 8 rings