users-permissions lifecycle are located inside the node_modules:
node_modules/strapi-plugin-users-permissions/models/User.js.
To add custom lifecycles you should use extensions, create a file under:
extensions/users-permissions/models/User.js with content:
'use strict';
/**
* Lifecycle callbacks for the `User` model.
*/
module.exports = {
lifecycles: {
// Called before an entry is created
beforeCreate(data) {
//do your magic here.
},
}
};