External Lookup field API

The plus sign (+) is a URL encoding replacement for a white space. In the context of URLs, it represents a space character.

However, SharePoint APIs expect spaces in field names to be replaced with, not a plus sign (+). This is likely why you're getting a 400 error - the URL is not recognized due to the incorrect encoding.

I am trying to send a GET Request as-  GET title('Detailed%20Production%20Status')?$select=Choices but workfront adds a plus sign in -  getbytitle%28%27Detailed+Production+Status%27%29?%24select=Choices. This results in the error code 4xx, forbidden. 

How to avoid this behavior?