How to enable PREEMPT_RT on Linux ubuntu 6.8.0-1057-qcom?

Hi Sir,

I want to enable PREEMPT_RT on Linux ubuntu 6.8.0-1057-qcom.
But there is no RT item - "Fully Preemptible Kernel (Real-Time)" in the kernel configuration.

General setup → Preemption Model → Fully Preemptible Kernel (Real-Time)

Could you let me know how to enable PREEMPT_RT on linux-qcom_6.8.0-1057.58?

This information for your reference
=======
ubuntu@ubuntu:~$ uname -a
Linux ubuntu 6.8.0-1057-qcom #58-Ubuntu SMP PREEMPT_DYNAMIC Tue Nov 25 14:21:46 UTC 2025 aarch64 aarch64 aarch64 GNU/Linux
=======

Also, I can successfully generate *.deb files on my device RB3Gen2.
As like:
linux-buildinfo-6.8.0-1057-qcom_6.8.0-1057.58_arm64.deb
linux-image-6.8.0-1057-qcom_6.8.0-1057.58_arm64.deb
linux-buildinfo-6.8.0-1057-qcom_6.8.0-1057.58_arm64.deb
linux-headers-6.8.0-1057-qcom_6.8.0-1057.58_arm64.deb
linux-libc-dev-qcom_6.8.0-1057.58_all.deb
linux-modules-6.8.0-1057-qcom_6.8.0-1057.58_arm64.deb
linux-qcom-headers-6.8.0-1057_6.8.0-1057.58_all.deb
linux-qcom-tools-6.8.0-1057_6.8.0-1057.58_arm64.deb
linux-tools-6.8.0-1057-qcom_6.8.0-1057.58_arm64.deb

Thanks

BR
Josen