How can x86 platform use kernel version 4.19.76

I found they have build kernel version 4.19.76,but the build scripts still use 3.18.25 kernel .
when the new kernel can be used?
or how can i use x86 platform kernel version 4.19.76?

kernel version 4.19.76, now 5.4 LTS, is used for creating a Debian buster based Volumio Version.
The current version will not get a new kernel anymore, too many changes, too much work, not worth the effort.
Its not only the kernel, a completely updated set of firmware and drivers for new hardware is just as important.
More info >>>here<<<