Can "AWS IAM Identity Center" be used to access APIs without running "aws configure sso" every other time?

Hi, yes, you to need refresh with a new aws sso login each time the session duration that you defined is reached.

See https://docs.aws.amazon.com/singlesignon/latest/userguide/howtosessionduration.html

For each permission set, you can specify a session duration to control the length of time 
that a user can be signed in to an AWS account. When the specified duration elapses, 
AWS signs the user out of the session.

When you create a new permission set, the session duration is set to 1 hour (in seconds) 
by default. The minimum session duration is 1 hour, and can be set to a maximum of 12 hours.
 IAM Identity Center automatically creates IAM roles in each assigned account for each permission 
set, and configures these roles with a maximum session duration of 12 hours.

I would also suggest reading https://ben11kehoe.medium.com/you-only-need-to-call-aws-sso-login-once-for-all-your-profiles-41a334e1b37e It does a very good job in explaining how aws sso login works, especially when it is used to get access to different applications.

Best,

Didier