Webp is a smaller file size than jpeg for the same image quality in almost all circumstances

For lower quality images sure, for high quality ones JPEG will beat it (WebP, being an old video format, only supports a quarter of the colour resolution than JPEG does, etc.) JPEG is actually so good that it still comes out ahead in a bunch of benchmarks, it's just it's now starting to show it's age technology wise (like WebP, it's limited to 8bpc in most cases)

It also doesn't hurt that Google ranked sites using WebP/AVIF higher than ones that aren't (via lighthouse).

Edit: I should clarify, this is the lossy mode. The lossless mode gives better compression than PNG, but is still limited to 8bpc, so can't store high bit depth, or HDR images, like PNG can.

Edit 2: s/bpp/bpc/