Google Assistant is an intelligent personal assistant developed by Google and announced at Google I/O May 2016. It is considered an extension of Google Now
Change build.prop info
1. Launch ES File Explorer. Swipe right to reveal the menu. Here, toggle the switch that reads “Root Explorer“.
2. Tap on “Root Explorer“, and then on “Mount R/W“. This will allow you to mount your system with Read/Write permissions.3. Here, mount “/system” as RW. Now change RO to RW, RW stands for Read/ Write.
4. Navigate to /system, and open build.prop. Then, tap on the three dot menu button, and tap on Edit.
5. Now Change this line “ro.product.model=your_device_name“. By default, this would have the name of your smartphone. Simply change it to “ro.product.model=Pixel XL“. Now, scroll down to the bottom of the build.prop file, and add a line that reads “ro.opa.eligible_device=true“.
Once you have done all that, simply reboot your device.
Now Clear GOOGLE APP DATA
go to Settings -> Apps. then select GOOGLE APP then Click on Manage Space then Click on CLEAR DATA.
Once you long press your home Button, you will see the Google Assistant welcome screen.