how do i transfer data from samsung to iPhone 6 plus?

Install the Google Photos and Google Calendar in your iPhone to transfer your photos, videos, and calendar. But it's a little painful to move the calendar that you have to go to Google Contact webpage to export contacts (vCard file) firstly, then import to your iCloud account.
I suggest you try these method included in this tutorial to transfer the contacts from your Samsung to iPhone, you can use the phone transfer tool to transfer most of the other data as well.

Don't read the reviews. Those are mostly Android fanboys:

https://play.google.com/store/apps/details?id=com.apple.movetoios&hl=en

Here are Apple's suggestions, details included.

Move from Android to iPhone, iPad, or iPod touch - Apple Support