Hi @prem0919 ,
I was able to see the splash screen while rebooting and shutdown.
Start by editing the below plymouth .service files
ls /lib/systemd/system/plymouth*
lib/systemd/system/plymouth-halt.service
/lib/systemd/system/plymouth-poweroff.service
/lib/systemd/system/plymouth-read-write.service
/lib/systemd/system/plymouth-start.service
/lib/systemd/system/plymouth-kexec.service
/lib/systemd/system/plymouth-quit.service
/lib/systemd/system/plymouth-reboot.service
/lib/systemd/system/plymouth-switch-root-initramfs.service
/lib/systemd/system/plymouth-log.service
/lib/systemd/system/plymouth-quit-wait.service
/lib/systemd/system/plymouth.service
/lib/systemd/system/plymouth-switch-root.service
Do the modification in plymouth-poweroff.service and plymouth-reboot.service for reboot and shutdown.
eg plymouth-reboot.service
[Service]
ExecStart=/sbin/plymouthd --mode=reboot --kernel-command-line="splash plymouth.ignore-serial-consoles" --pid-file=/run/plymouth/pid --attach-to-session
save and reboot.
Let me know the results after testing.