Access tokens are by default set to valid for 24hours. You can't change/extend expiry of access token.
In addition JWT Tokens are an open standard. Using a standard or open source library along with their private key to programmatically generate a JWT tokens. They then use their own generated JWT token to authenticate with adobe.io and exchange it for an API access token to use in subsequent calls to interact with adobe campaign.
You can use libraries listed here to setup token exchange programmatically.