If you want to add nosniif, CORS, HTTP Strict-Transport-Security, Clickjack, and X-Xss-Protection headers to a particular user or domain you can add them using the user level Apache includes. It is best to use the Apache includes because they may not get applied when added in .htaccess files.
You first need to create the paths for the includes if they do not already exist. Let's say the user name is fastcar and the domain is fastcar.com you would create the following paths like this
mkdir -p /etc/apache2/conf.d/userdata/std/2_4/fastcar/fastcar.com/
mkdir -p /etc/apache2/conf.d/userdata/ssl/2_4/fastcar/fastcar.com/
Next, you can create a .conf file and place it in either /etc/apache2/conf.d/userdata/ssl/2_4/fastcar/ to be loaded for all domains under the user fastcar or you can create a .conf file for just one domain by creating the domains folder under that user and place the .conf file in that folder. In this example, the .conf file will be for fastcar.conf.
The files then to create would be uniquely named something like
Note: one has std for port 80 and one has ssl for port 443 ssl access
Then in each file put the following content:
# Disable content sniffing, since it's an attack vector.
Header always set X-Content-Type-Options "nosniff"
# Disable Proxy header, since it's an attack vector.
RequestHeader unset Proxy
# Add CORS-Header
Header set Access-Control-Allow-Origin "*"
Header set Access-Control-Allow-Methods "GET"
Header always set Strict-Transport-Security "max-age=31536000; includeSubDomains"
# Referrer Policy
Header always set Referrer-Policy "strict-origin-when-cross-origin"
# Clickjack Attack
Header always set X-Frame-Options "SAMEORIGIN"
Header always set X-Xss-Protection "1; mode=block"
Then we need to rebuild httpd.conf so those includes get added with
and then APache restart with