How to automatically start logstash

/opt/logstash/bin/logstash -f logstash-apache.conf
is not equivalent to systemctl start logstash
even though the only file in /etc/logstash/conf.d is logstash-apache.conf

Please advise.

What do you mean?
Why is it not equivalent?
What do you expect?

Please put more effort into your posts. Not explaining things makes it very hard to provide meaningful assistance. I would encourage you to read Elastic Stack Help · Forums and IRC | Elastic as well.