im noticing that the iphone 6 plus are not able to send the special features like the confetti or the balloon with a texts

It seems you should be, however understand it has to be an iMessage. A regular SMS message cannot use it. See this page from the iPhone User Guide. http://help.apple.com/iphone/10/#/iph3d4cb79c9

You might also want to take a look at this support document Use message effects with iMessage on your iPhone, iPad, and iPod touch - Apple Support explaining message effects.

Those are features of iOS 10. Have updated your iPhone 6+ to iOS 10?

Make sure you have Settings>General>Accessibility>Reduce Motion set to Off.

I have this feature on my iPhone 6 so the 6+ should be able to do it.