WhatsApp new update increases the WhatsApp Group calling limit from 4 participants to 8 participants including you. WhatsApp currently updated this new update in the WhatsApp Beta version v2.20.135. Also, this update will be rolled out to all users including Android, iOS for both stable & beta users. So to get this feature firstly, update the WhatsApp to the latest version through Google Play store. WhatsApp already rolled out this feature to maximum users if in case you would not receive the update means just wait and it will be received in a couple of days. 
Therefore, you can make group calls for up to 8 users including you and it will be applicable for both Voice & Video calls. Similarly, for WhatsApp groups with less than or equal to 8 participants group call can be made directly to all participants instantly on single taping inside the WhatsApp Group call option. 
If you guys received this new WhatsApp update let me know how it works on the comments below,