No, there is no way to access the RTSP stream. Let me explain a little about XProtect VMS streaming overview simply.
Cameras connect to Recording Server on VMS and clients (such as Smart Client) also connect to the Recording Server to fetch recording or live video to see. Milestone do not support RTSP-streaming, these connections are established by Milestone protocol.
Please see this similar question mentioning about RTSP in question 2 –
https://developer.milestonesys.com/s/question/0D50O00003EIrqISAT/sdk-support
You might be interested in Open Network Bridge (also known as Onvif Bridge), please see this document -