how do I get my iphone8s to send & receive email?

See this, If you can't receive email on your iPhone, iPad, or iPod touch - Apple Support and this, If you can’t send email on your iPhone, iPad, or iPod touch - Apple Support

Have you installed a mail account on the phone? Are you seeing an error when you attempt to send or receive mail?

What is the error?

Repeating Lawrence's question, what is the error you are seeing. That will help tremendously to identify the problem. Also, who is the email provider? i.e. Gmail, Yahoo, Xfinity or other ISP?