How to export split video separately when editing complete video??

There are a couple of options you could try:

• Export the full video from Premiere Rush and then trim it using Adobe Express:
  • Adobe Express - Trim your video for free.
• Make sure that Sync is enabled for your project, open it in Premiere Pro by clicking Open Premiere Rush Project at the bottom left of the Premiere Pro home screen, set Mark In and/or Mark Out where you want, and export.