Benefits for opening a 529 as an older parent?

I will be 61 when my son graduates from high school (unless he is some prodigy). So I will be able to pull penalty-free from my 401k and Roth IRA by then. Is it worth also opening a 529 or better to just keep maxing 401k and Roth IRA with the idea that I'll use funds from those accounts for his higher education expenses?

I haven't read anything noting any extra benefit for a 529 in my situation where I would be able to pull from existing accounts. I feel like my 401k is in good shape for my age. As long as markets don't go totally awry in the next 18 years, I don't have concerns about paying for undergraduate or a trade school and also being comfortable in my retirement. (My partner's retirement funding is behind where it should be, so right now I do not expect them to go 50/50 with me on our son's higher education expenses.)

And this isn't an either/or. I could put like $100/month into a 529, but is there any extra benefit?