It looks like that JSON response is coming from the server/API?
It looks like you are sending a 4MB size request, when the limit is 1MB.
So if you need to increase the size limit then it would be a HTTP server side setting.
The HTTP client (browser or other user agent like Postman) can have its own limitations.
I’m not aware of any limits on the request size in Postman, but there is on the response size which is set to 50mb as default (but can be changed in the settings).
@gbadebo-bello might be able to advise if there are any such client side limitations in the Web Client.
If this is against the Postman Mock service, then if I remember rightly it has a 1 MB limit (which can’t be changed).