If you using Amazon Linux 2 AMI you need to follow these steps:

- In AMI2 they are using systemctl for managing services check if it is installed on your machine 2.systemctl list-units --type=service by this command check if httpd is listed
- sudo systemctl enable httpd 
    To eanable httpd start on boot up
- systemctl is-enabled httpd 
    To check if httpd enabled to start on boot up linux system

After that you can reboot your linux system and httpd will be started.