I have Android 9 in my phone and have WhatsApp version 2.19.258 installed on it. Now, I wish to hide/change the display picture of a certain contact, say Mr. Alex on my phone. How do I go about doing it?
You can't change someone else's profile picture on WhatsApp. You can only change your own. There was a bug in WhatsApp that used to show whatever photo you add to the contact in your phone's contacts app instead of their actual profile picture on WhatsApp but now it's fixed I guess.