:shrug: there is a wide variety of positions covered under dou'lo, and Christians are told to treat all of them as their equals.
Yes, specifically it says that if you are the master of a house, then you must treat the people who serve in it as your equals, and seek to serve them. Where they are "owned", rather than being a bondservant etc/ type, the New Testament advice (though not the demand) is to set them free, but the requirement is that you treat them as an equal and seek to serve them as Christ served you, and as you are called to serve Him. If you are a dou'lo, and you can seek freedom, you should do so, but that is less important than serving others around you as Christ served you, and as you are called to serve Him.
Christianity demands that the abuses be stripped from the master/servant relationship, regardless of the specifics. Within that demand, it became a debate whether or not you could keep the institution of slavery at all, a debate that the abolitionists eventually won.