Mary, There is no easy way to block emails on your iPhone directly. You will have to set up the rules using a computer. If you are using GMAIL, you can read the instructions at:
If you are using your iCloud email account, here are some instructions:
Having said that, you can however easily flag the email and move it to your junk folder on your iPhone 7+. You can look into email apps such as Spark that allow additional features.