The post you linked to is accurate in that the ID Token has a default lifetime of 1 hour, however, there has been a feature released since that time that does allow you to modify the ID Token expiration. You can set up an endpoint for a Token Inline Hook that modifies the claims within the token(s), including the exp claim.
You can read more about this feature and how to implement it here: https://developer.okta.com/docs/reference/token-hook/#sample-response-to-modify-token-lifetime. Note that this does require the use a Custom Authorization Server (such as default and the ones you can create with the API Access Management feature).