No it’s not. (At least for shared hosting or a managed VPS)
While there was once a way to accomplish this, it’s been gone for many years because it created security issue.
Through the dreamhost panel a ‘user’ assignment is made for each hosted domain or sub-domain. The listed “user” is how apache knows where to find the files for that web space. There is no way to create access across users or create a “master” user.
Of course a dedicated server or dreamcompute instance can be configured however you want.
I currently have a non-DH dedi-server with a few low-traffic sites of mine plus those of some family/friends/colleagues. With a change in my business activities, site traffic will lessen and hence switching to shared is sensible…
But I need a host where I can set a few ftp accounts so someone can poke around with their own stuff and preferably I can access them all (when asked to sort something) through my ftp.
My brain is fading… with DH, could/would I then setup a user to have ftp access to a specified domain, and another user to a different specified domain, etcetera - so that each can sort their own stuff, and if they need me to do something for them I’d need to login using their ftp?