Check out the demo farm.
They are re-built every night so any changes you make or data you add will disappear by the next day.
Here’s where you can get access to a development version of 6.0 with and without demo data.
https://www.open-emr.org/wiki/index.php/Development_6.0.0_Demo
Here’s where you can try out some demos using OpenEMR version 5.0.2
https://www.open-emr.org/wiki/index.php/Development_5.0.2_Demo
If you fork OpenEMR to a branch on your own github repository you can request that a demo be made based on your copy of OpenEMR to test out new capabilities.