a.cs

public class Example
{
  public event EventHandler<string> PassString;
  public event EventHandler<( Keys key, int x, bool modified )> PassMultipleValues;

  private void NotifySubscribers()
  {
    PassString?.Invoke( this, "some text" );
    PassMultipleValues?.Invoke( this, ( Keys.Up, 1, true ) );
  }
}

...

public class Main
{
  private Example _example = new();
  
  public Main()
  {
    _example.PassString += OnPassString();
    _example.PassMultipleValues += ( _, e ) => SomeOtherMethod( e.key, e.x, e.modified );
  }
  
  private void OnPassString( object sender, string text )
  {
  }
}