I am on the growth plan. I would like to have a dev subdomain to use in addition to domain_name/version-test/ method of previewing. Is this possible?
No it is not.
— although there is a hacky way of doing so. You might be able to use an iFrame, but you’d need to link the frame’s urls to whatever iFrame you’re using to serve it. Doesn’t sound too fun 
Thank you.