Reviewed this thread https://www.googlecloudcommunity.com/gc/Apigee/Apigee-X-Support-for-SOAP-Webservices/m-p/419360
If requirement is to create Apigee SOAP proxies using WSDL ,
Managment plane (for Apigee-X and Apigee runtime) was missing that option in UI .
It indicates REST proxies creation with OpenAPISpec, Reverse proxy, No proxy and upload proxy bundle option. Did not see option of creation of SOAP proxies, using existing WSDL . This requirment is not for passthro.. SOAP proxies
Let me know if missing anything.
This answer is still pertinent.