As I understand it, Arpeggio is a playing technique - instead of holding down the notes of the chord for the time of the chord, they are added in rising sequence over the timeof the chord
On the assumption that you are using a MIDI keyboard controller or writing the notes in the MIDI editor then it is the players responsibility to play the chords as required.
If you are using the preset sequences of the synthesizers then once they are on the timeline you can edit the chords in the Midi Editor to make them Arpeggio.
Since you are asking, I assume you already know what an arpeggiator is and what it does. Prior to the development of synthesizers in the 1970's, arpeggio's were strictly a playing technique. As mentioned, beginning with the early synthesizers, the arpeggiator became a feature that played preset arpeggio's determined by the pattern selected and the keys that are held down. Arpeggiations can be set to one, two , three or more octaves. The basic patterns are UP, DOWN, and UP/DOWN. Other random or programmed patterns are possible.
Third-party arpeggiator plug-ins are available. You can find them with a simple Google search for "arpeggiator plug in". I don't know if, or how well, they can be incorporated into MAGIX Music Maker. They may require a full-fledged DAW software.
I am working on techno style music, so that is why I really need synth with arpeggio to make the synth sound into trance sound. ( I think you know what I am talking about :) The expensive synthisizers all have it, it is just I can not afford one yet. That is why I wonder if could find something similar in MMM 2013 or any others?