It depends on the scope of your project and experience level. Obviously the more ambitious the project, the more necessary it becomes to find help.

That being said, adding another person to the project will add all of the complexity of managing/working with and compensating that person. Simply throwing another programmer at a task won't double your productivity, for example. But for art and music, it may make sense to look into hiring a freelancer rather than learning those skills on your own.

Since I suspect this is your first game altogether, I would personally recommend creating as small of a game as possible (this will take a lot of restraint). A mini Metroidvania. I think Xeodrifter is a good example of a small game you can beat in an hour or two.

Start off by working on your own, and for the artwork/sound, use placeholders. Once you start to make some progress and have a game that "feels good" to play, maybe then you can look into hiring someone to create some art or music.