Nope, Qt 6 still uses moc. I don't think modern C++ metaprogramming is quite capable of entirely replacing moc. The closest thing I'm aware of is [0], but it requires additional macros compared to what moc requires, and compilation speed can suffer. Chances are moc won't be dropped until full reflection lands, if ever, and even then if compilation speed is too bad I wouldn't be entirely surprised if moc remains.
[0]: https://github.com/woboq/verdigris