@Dnyaneshwar Surywanshi Thanks for reaching out. As you want to expose your azure function API using APIM then you can refer to this document to Import an Azure Function App as an API in Azure API Management.
In case if you are looking to directly call the Dynamics 365 API from the APIM then you can refer to Add an APIM manually to the APIM. Now you need to build the request as per the Dynamic 365 documentation and you can refer to APIM policy or advance policy to generate the request and pass the right authentication.