You should configure your Apache as reverse proxy:
https://httpd.apache.org/docs/2.4/mod/mod_proxy.html#forwardreverse
In my setup, Bitwarden is listening locally on port 4480 with SSL turned off. I configured a virtual host for https://bitwarden.mydomain.com
which sends all requests to Bitwarden like this:
SSLProxyEngine On
RequestHeader set Front-End-Https "On"
ProxyPreserveHost On
SSLProxyVerify none
SSLProxyCheckPeerCN off
SSLProxyCheckPeerName off
SSLProxyCheckPeerExpire off
ProxyPass / http://127.0.0.1:4480/
ProxyPassReverse / http://127.0.0.1:4480/
Certificates for this virtual host are generated separately, not by Bitwarden.