See: https://httpd.apache.org/docs/current/mod/mod_proxy.html

Apache mod_proxy library: The ability to use Apache as a reverse proxy is provided through a shared library named mod_proxy.so. This module is not enabled by default, so you must edit Apache’s httpd.conf file to enable it. You also need to enable Apache’s mod_proxy_http.so shared library.

Enable the mod_proxy and mod_http modules in Apache’s httpd.conf file. Uncomment the appropriate lines in Apache’s httpd.conf file to enable the Apache mod_proxy and mod_proxy_http modules. Note that this may not apply to newer versions of Apache2 and Ubuntu. SEE BELOW

### Enable LoadModule entry for Apache mod_proxy and mod_proxy_http ###
#LoadModule proxy_fcgi_module modules/mod_proxy_fcgi.so
LoadModule proxy_module modules/mod_proxy.so
LoadModule proxy_http_module modules/mod_proxy_http.so
#LoadModule proxy_scgi_module modules/mod_proxy_scgi.so

Instead, maybe enable the appropriate apache proxy modules:

sudo a2enmod proxy

sudo a2enmod proxy_http

Example of Reverse Proxy/Gateway in apache virtual hosts file.

Reverse Proxy
ProxyPass "/foo" "http://foo.example.com/bar"
ProxyPassReverse "/foo" "http://foo.example.com/bar"

SEE the following PER ABOVE This is from Ubuntu server guide

https://assets.ubuntu.com/v1/09200365-ubuntu-server-guide-2023-07-11.pdf

Configure apache2
Apache2 is configured by placing directives in plain text configuration files in /etc/apache2/. These directives are
separated between the following files and directories:
244
Files
• apache2.conf
The main Apache2 configuration file. Contains settings that are global to Apache2.
Note: Historically, the main Apache2 configuration file was httpd.conf, named after the “httpd”
daemon. In other distributions (or older versions of Ubuntu), the file might be present. In modern
releases of Ubuntu, all configuration options have been moved to apache2.conf and the below referenced
directories and httpd.conf no longer exists.
• envvars
File where Apache2 environment variables are set.
• magic
Instructions for determining MIME type based on the first few bytes of a file.
• ports.conf
Houses the directives that determine which TCP ports Apache2 is listening on

Tutorial - Running a Reverse Proxy in Apache

http://www.apachetutor.org/admin/reverseproxies