The people @plesk builded a nice extension for converting htaccess content to nginx directives. Keep in mind : for plesk 11.5 and up !
Use the following plesk extension : “https://ext.plesk.com/packages/b33b9ba7-72c7-43a5-8454-f58236340563-htaccess-to-nginx”
Go to your hosting configuration in Plesk :
Redirect / https://domain.com/
All http requests will be redirected to https://domain.com