Per-website hosting settings can be divided into the following groups:
Hosting type, security, scripting and statistics settings. See General Settings.
Web scripting (PHP or ASP.NET).
PHP scripting language settings. See PHP Settings or ASP.NET Settings.
Web Server (Apache&nginx or IIS)
Web server settings. Web server type depends on the operating system of your Plesk server: Apache (with nginx) is used on Plesk for Linux, and IIS on Plesk for Windows. See Apache Web Server Settings and IIS Web Server Settings correspondingly.
Note that in the IIS web server settings you can configure basic website security settings, such as anonymous access, ssl usage, and directory browsing.
On Windows, you can also set up custom ASP.NET settings in Websites & Domains > select a domain > ASP.NET Settings. For details, see ASP.NET Settings (Windows).