At the moment, the certs would need to be updated manually inside the Okta administrative panel before the old ones expire, in order to provide consistency in the HTTPS traffic.
I’d like to encourage you to raise this as a new feature request over our Okta Community by going to your Okta Admin Panel >> Help and Training >> Product >> Ideas. Features suggested in our community are reviewed and can be voted and commented on by other members of the community, therefore making it much easier for the engineering team to understand the priorities that you have for feature requests.
Once feature requests are submitted they are visible to other Okta admins, who can vote on them to provide more visibility. Using this method will allow you to maintain visibility on your feature requests throughout the process.