How do I update the IOS on my Macbook Pro?

The only thing we know is that you have a 13" MacBook Pro that is running macOS Sierra. What exact model is your notebook and what version of macOS do you want to upgrade it to?

Ref: For example, for Big Sur: How to upgrade to macOS Big Sur - Apple Support

iOS only runs on mobile devices like the iPhone.

If you mean MacOS please tell us what model/year computer you have and what operating system version you are currently running.