David you in the correct place and with the correct vendor , Juniper are better than most in this respect.
#1 if you want something already set up
Juniper vLabs - Juniper Networks
#2 what Steve Puluka just said, I use EVE-NG a lot to POC and educate myself. and Juniper has vSRX vMX and vEX available to download last time I looked,
This is massive benefit of Juniper and some other vendors make it hard work to get virtual versions.
@Juniper don't stop making the these version available for free its a critical tool, I know they are not always perfect but of the VMs are 90% of the way there that's good enough.
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