Unable to initialize graphical environment. Most likely cause of failure, is that the tool was not run using a graphical environment? Please either start your graphical user interface or set your DISPLAY variable.
I can not get authconfig-gtk to launch, my system is set to graphical and yet it does not work, how do I get it to work to configure ldap via gui?
you don't - at least not in rhel 8. it is deprecated and replaced by authselect. The easiest way I've found is to install nslcd and nss-pam-ldapd (also deprecated), copy/edit the sssd configuration replacing sss with ldap. The ver 8 release notes talk about moving away from OpenLDAP towards 389 DS as "justification" (YMMV) but that's the thinking.