Currently WebP support of major browsers is as follows:
✓ Google Chrome (Desktop + Mobile versions, since 2011)
✓ Firefox (Desktop + Mobile versions, since Version 65, January 2019)
✓ Opera (Desktop + Mobile versions, since 2011)
✓ EDGE (since Version 18, Novemeber 2018)
✗ IE (Desktop + Mobile versions)
✓ Safari (Desktop + Mobile versions)
That means, all major browsers as well as some less popular browsers support WebP.
Together these browsers add up to 90+% of all internet users being able to see WebP images.
Source: https://caniuse.com