do you mean transferred to the new owner?? If yes, then yes! Otherwise how is the buyer going to use their newly purchased domain if they can't transfer it out from you?
But depending on the domain registrar the buyer might only need a push, it's happened to some of the domains / sites I had in the past. The domains have been purchased through Namesilo and the buyer also had a Namesilo account and - after purchase - I just contacted NS support and they've pushed the domain from my NS account to the buyer's NS account.
So, if the buyer has an account with the same registrar that you used for this domain, and if they're OK with having the domain pushed to their account this is a hassle-free way of "transferring" the domain out from you. And it takes only a few minutes, so it's fast too...
But if they use different registrars then yes, you'd have to transfer the domain out to them... or I think they are the ones who need to transfer it, I don't remember the exact procedure but it can be assisted / done by the support staff of your buyer's domain registrar, so no problem for you here. The only thing you must do before transfer is to unlock the domain in your registrar's account (in case that it's locked - which it should be btw! - otherwise there's nothing else for you to do I believe)...
But anyway, my feeling is that - unless they have value - domain names are very hard to sell as they are, so I would say put a website on it first.
Even if it's just a placeholder website for showcasing purposes you might still be able to get a better deal than if you were to sell the domain alone. This is particularly important if the domain is not worth more than... I don't know... say $50-60 or so. Some domain selling platforms might even ask for a listing fee... or even a listing (once-off) fee and then a monthly listing fee, I think Flippa does something like this, which makes selling low value domain there worthless IMO...
But if you put a website on it (say, with 10-20 quality articles and a few good links pointing to a few important pages like the homepage and a few main category pages) to up its DR to around 5... even if this is not much, when taken along with the (pretty good otherwise) domain name I am sure you can sell it for more than it's worth.
That's what I would do anyway....
