This app was mentioned in 10 comments, with an average of 1.70 upvotes
If your main concern is to get iOS-looking emoji, you can install Textra for SMS messaging, and then install this add-on to configure Textra to display emojis a la iOS.
Installing fonts is, as someone else has already said, a little more advanced and will stop a number of apps working if you're rooted or have an unlocked bootloader. So, using a custom SMS app like Textra and changing the way emojis are displayed there might be your best bet.
I have no idea if you can change emoji system wide, even with root, and even if you could, WhatsApp emoji would look different anyway.
Hope this helps!
If you just want it for texting then get Textra for your messaging app. They have emoji packs that you can download. Lots of my friends have iPhones so I just use the ios emoji pack.
https://play.google.com/store/apps/details?id=com.textra.emoji
Obviously that's only for SMS but I use Textra myself and it's the best SMS app out there; the iOS emoji compatibility is just a big plus. You can get the iOS emoji addon here, although I personally prefer the Twitter emoji. Either way though it'll work 100% with your iOS friends when texting.
There is a way to change the emoji if you are texting. You need to get the Textra app for texting, its much better than the stock Messaging app. Then you will need to download "Textra Emoji - IOS style" (https://play.google.com/store/apps/details?id=com.textra.emoji&hl=en)
Afterward, your emoji in the Textra app will be like that on iOS. This only work for the Textra app, not system wide. For that, you need root.
yep just have to download the module pack off the Play Store separately. https://play.google.com/store/apps/details?id=com.textra.emoji
~~Apple made them take it down but I still have the apk. Pm me if you want it~~
Edit: it's back on the Play Store here
Maybe it looks like they mightve trumped them with an all update. I don't use Textra no more but I still see them on the store https://play.google.com/store/apps/details?id=com.textra.emoji
You have to download the plug-in from the Play Store. Here you go.