You can keep your game progress separate by using different Google Accounts.

Follow these steps:

1. Create a new Google account (or use any other). Follow the official Google instructions here

2. Add this account on the device settings.  Go to Settings - Accounts - Add account. 

3. Change account for games on the Play Games app:

1. Open the Play Games app on your device 
2. Choose Settings from the three dots menu
3. Find Change account for games