Linux kernel 6.6 is available for download right now directly from Linus Torvalds’ Git tree or from the kernel.org website. However, you’ll have to compile it on your GNU/Linux distribution. If that’s not your cup of tea, you’ll have to wait for Linux 6.6 to arrive in your distro’s stable software repositories.
Can we use this now. If so how?
If you really want it right now, many guides for how to compile linux kernels are available. Here’s one.