I don’t have a forwarding option

The option is on your iPhone as you would have seen in the Related Article. However, if you don't see it, this is a kind of hidden explanation in the article.

* Don't see the Text Message Forwarding setting on your iPhone? Go to Settings > Messages, turn off iMessage, turn it back on, tap Send & Receive, tap Use Your Apple ID for iMessage, then sign in with the same Apple ID used on your other devices.

What happens when you try the procedure in the article linked

above your name?

At what step does the process fail?

If there is an error message, what is the exact

complete text of that error message?

You need to provide more information before someone may offer a solution.