If you want to set a full size image on your whatsapp profile pic and you don't know how to do that, then you are at right place.
Here i am going to tell you the trick, but you need to install a third party app before do this.There are a lot of apps in Google's play store. some of them are-
You can use any one of them to set a square size image, i personaly preffered No crop for doing this trick.
Step 1 - : Install the app on your device.
Step 2 - : Select image from gallary or capture new one from camera.
Step 3 - : Edit the iamge if you want otherwise select Share icon from top right corner.
Step 4 - : Save image by clicking on save button.
Step 5 - : Now you can set this image on your whatsapp profile picture.
Here is the result -
Note - the result image is same, background is change due to its transprancy.