Se li estus riĉa, li havus multajn amikojn = If he were rich, he would have many friends.
Amataj kaj estimataj de ĉiuj, la fratoj havis multajn amikojn = Loved and esteemed by all, the brothers had many friends.
La batalo apud Farsalo ŝanĝis multajn aferojn en Romo = The battle near Pharsalia changed many things in Rome.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "multajn" in a variety of sentences. We hope that you will now be able to make sentences using this word.