As a newbie that may be a little outside my expertise. Perplexity says "To find the src/config.php file, navigate to the root directory where you installed XenForo on your web server. Inside this directory, you should see a folder named src. The config.php file is located within this src folder."
I'm only comfortable using the admin control panel. I don't think I want to dig around in the server where it's all installed. Also I had someone else install it. I could have learned how myself but I wanted it done that day.