Data usage depends solely on the user of the device. I have 2 iPhone 6s, 1 iPhone 5S and 1 Droid Maxx on my account. We normally use ~4 GB of data TOTAL in a month and that is TRYING to use more data towards the end of the month.
Just because you get a newer phone does not mean your data usage will go up. It completely depends on you.
You're welcome, and just be careful of how you buy, what you buy (plan and phone) and how you use it.