Start Okta web session with RefreshToken

I am developing a custom iOS app that is basically a browser wrapper that can be used to access several Okta-protected (SAML) internal websites of my company.
When the user launches the app for the first time he/she would have to provide credentials/MFA and then the RefreshToken is generated and stored on the phone (iOS keychain).
After this first step, whenever the app is launched again: How can I use the RefreshToken to start a new browser session with Okta (and authenticate the user successfully without prompting the user for credentials/MFA again)?
I am thinking if there is a Okta URL that I can open in my embedded app browser (including the RefreshToken as one of the parameters) to start a new Okta web session (create Okta’s “sid” Cookie)?

Any help is much appreciated!