a JSON-object sound like it will be several hundred or even thousand bytes.
This is doable but it might need sending the data in several chunks or to increase the receive-buffer of the ESP-2 that the receive-buffer can hold the whole content.
Serial sends the data bytewise. There might be some details to tweak but I guess this kind of tweaking is pretty interesting to the advanced users here.
So if you encounter a problem just post it here.
best regards Stefan