No, I’m talking about the Linux kernel. You can check this for yourself. Take a look at the roms distributed on LineageOS as the example project and see if they include kernels that are up to date in any way. For older phones outside of vendor support, those kernels will always be out of date.

Some diligent LineageOS projects are known to incorporate some open source kernel fixes sometimes, or grab newer blobs from other phones from other devices. But there’s only so much to they can do. In general, it’s true to say that older devices with community Android support are not completely up to date - the kernels are old, and vendor drivers are not getting updated. Outside of making big usability concessions in projects like Replicant, the community can’t do much here.