# vi /usr/lib/virtualbox/vboxautostart-service.sh

start() {
...
        # Commented this line, is not working, does not start VM.
        # Added "echo" to debug variables show correct values in /var/log/messages (attached).
        # start_daemon "$user" "$binary" $PARAMS > /dev/null 2>&1

        # Added below line, may start or not VM manually from cmd line, but does not start VM when invoked at boot 
        su - $user -c "/usr/lib/virtualbox/VBoxAutostart $PARAMS" > /dev/null 2>&1

        # Finally, added below line, starts VM both manually from cmd line and when invoked on boot.
        su - $user -c "/usr/lib/virtualbox/VBoxHeadless --startvm olservice01 --comment olservice01 --vrde on &" > /dev/null 2>&1		
...
stop() {
...
        # Commented this line, is not working, does not stop VM, upon boot the status as if killed and not by poweroff.
        # start_daemon "$user" "$binary" $PARAMS > /dev/null 2>&1

        # Added below line, may stop or not VM manually from cmd line, may not stop VM on host shutdown.
        su - $user -c "/usr/lib/virtualbox/VBoxAutostart $PARAMS" > /dev/null 2>&1

        # Added below line, stops VM manually from cmd line and may stop VM on host shutdown.
	su - $user -c "/usr/lib/virtualbox/VBoxManage controlvm olservice01 poweroff" > /dev/null 2>&1
...

The oracle.start file was created by oracle user which belongs to vboxusers, using this command.
[oracle@ols8001 ~]$ VBoxManage modifyvm olservice01 --autostart-enabled on

And for the attempt to have it stopped used this command, though does not have any change to autostart service results.
[oracle@ols8001 ~]$ VBoxManage setextradata olservice01 autostop poweroff
[oracle@ols8001 ~]$ VBoxManage getextradata olservice01 autostop
Value: poweroff

[root@ols8001 ~]# ls -la /etc/vbox/
total 24
drwxrwxr-t.   2 root   vboxusers    51 Oct  2 13:38 .
drwxr-xr-x. 171 root   root      12288 Oct 23 19:13 ..
-rw-------    1 oracle oinstall      1 Oct  2 13:33 oracle.start
-rw-------    1 oracle oinstall      1 Oct  2 13:35 oracle.stop 
-rw-r--r--.   1 root   root        189 Mar 18  2021 vboxautostart.cfg

[root@ols8001 ~]# ls -la /etc/default/virtualbox
-rw-r--r-- 1 root root 143 Oct  2 13:48 /etc/default/virtualbox

[root@ols8001 ~]# cat /etc/default/virtualbox
# virtualbox defaults file
VBOXAUTOSTART_DB=/etc/vbox
VBOXAUTOSTART_CONFIG=/etc/vbox/vboxautostart.cfg
SHUTDOWN_USERS=oracle
SHUTDOWN=poweroff

[root@ols8001 ~]# cat /etc/vbox/oracle.start
1
[root@ols8001 ~]# cat /etc/vbox/oracle.stop
1

[root@ols8001 ~]# cat /etc/vbox/vboxautostart.cfg
# Default policy is to deny starting a VM, the other option is "allow"
default_policy = deny

## As root create an entry for each user allowed to run autostart
oracle = {
   allow = true
}