Impersonate OKTA signed in user in core web api

Apologies up front if this question is in the wrong forum as I am new to OKTA development.

I have an core Web API REST endpoint that as part of its function connects to Jira REST endpoints. I want to be able to flow the OKTA credentials to Jira of the calling user so I don’t get 401s or need username/password.

For context, I am able to directly invoke the JIRA end-points from the web browser after having logged in to Jira via OKTA.

I’ve tried using WindowsIdentity.RunImpersonated without success.

Any suggestions as to how I should be approaching this would be gratefully received.

Thanks in advance.