What version of iOS are you running on this iPhone 7?
Where are you looking when you find your photos out of order?
If you are running iOS 11.something, and you are looking in the "Photos" view (also known as Years, Collections, and Moments; represented by the two-stacked-rectangles icon on the lower left, and your photos there are not in the order taken (and clustered by location), then something is wrong.
If you are running iOS 11.something, and you are looking in the "All Photos" album in the "Albums" view (represented by the three-stacked-rectangles icon on the lower right), the photos are supposed to be in order by date added, and you just added all of your photos when you transferred them to this phone, so they might well not be order taken.
If you have an older iOS than 11, or if you are looking somewhere else, let us know what level and where you are looking.
I am running iOS 11.2.5 and its out of order in my camera roll album, but its perfectly normal in my photos tab, and its very frustrating trying to find photos in my camera roll album to send to people because they are all out of order.
Sorry, I tend to forget that people who don't have iCloud Photo Library enabled see a "Camera Roll" view instead of (or in addition to?) "All Photos". (I enabled iCPL, so I don't see a Camera Roll on any of my devices.)
The issue of photos being out of order in Camera Roll under iOS 11 has been reported by a number of users here since iOS 11 came out. The closest thing to a fix anybody has reported is fairly technical and not for the faint-hearted. (I also couldn't say whether it works or not, or whether the explanation for the problem is the same as the one I offered for iCPL users.) A couple of users reported being told by Apple that it was a known error that might be fixed in a future iOS release.
Sorry I couldn't offer better news.
Any special reason you can't send photos from your Photos tab where you say things are normal?
my photos aren’t in chronological oder after changing phones
