How to pass data to create a user to IdentityServer from another api project?

Question

ASP.NET

Hello. I have a task of transferring data from a Web Api project to IdentityServer (in this project I have a controller that is responsible for working with users).

How can I securely pass data from Web Api to IdentityServer api? Can I somehow do a redirect with data transfer to the desired endpoint, or can you suggest something else. I will be very glad to any possible advice, links, etc. If I created the IdentityServer -> WebApi dependency, I could use UserManager and explicitly create users in the Wep Api controller, but this option is clearly not suitable. I am a beginner and this is my first time working with this problem. Thank you.