Step 1: Settings  > Battery and device care > Battery

• Background usage limits
  • Put unused apps to sleep > Turn OFF 

• More battery settings
  • Adaptive battery > Turn OFF

Step 2: Settings > Battery and device care > Menu button > Select Automation

• Auto optimize daily > Turn OFF
• Adaptive power saving > Turn OFF

Step 3: Settings  > Battery and device care > Memory > Excludes apps > Add apps & WhatsApp Service > Add

Step 4: Settings  > Apps > WhatsApp Service > Mobile data > Allow background data usage & Allow data usage while Data saver is on > Turn ON

  

 

Step 5: Settings > Apps > WhatsApp Service > Permissions > Location > Allow all the time

Step 6: Hide app on the home screen

1. Swipe up to open the App Drawer from the home screen
2. Tap the three dots on the top-right edge of the screen
3. Select "Settings" > Select "Hide apps"
4. Select "WhatsApp Service"
5. Done