You can use scripts from this website to modify your server in different ways. Find more information on SkUnity.com!
Install the skript minecraft plugin. Now go to the Scripts tab to select a script file you want to add to your server. Open your plugins folder, then navigate to: Skript > scripts. Now drag and drop the script file you installed (.sk) in the scripts folder. Now restart your server or use the command /sk reload <script> to reload a specific skript. Or using the command /sk reload scripts to reload all scripts. This may take a little while if you have more than 1 scripts installed.