I haven't follow the trend much nor seen a recent comparison, so take this with a grain of salt.
WebP is based on VP8, which was considered to be competitor to H.264 (AVC). HEIC is based on H.265 (HEVC), which competes with VP9 and AV1. So I'd assume WebP is one generation behind HEIC. WebP was introduced 5 years before HEIC though.
Correct. WebP is 10 years old, based on the VP8 codec that is about 14 years old, which lost in the market to H.264 that is 17 years old. In video streaming VP8 has been completely replaced by VP9 years ago, and VP9 was going to be replaced by VP10 which became part of AV1.
So WebP is hardly new, and a couple of generations behind. Now the next hotness is AVIF (or maybe JPEG XL), so ironically, WebP is becoming usable and obsolete at the same time.
WebP is based on VP8, which was considered to be competitor to H.264 (AVC). HEIC is based on H.265 (HEVC), which competes with VP9 and AV1. So I'd assume WebP is one generation behind HEIC. WebP was introduced 5 years before HEIC though.