需要先调用downloadFile，具体请参考

https://developers.weixin.qq.com/community/develop/doc/000e421d6cc228fcb1ea86c7c51400?_at=1655950249337

let path = `https://wx.qlogo.cn/mmhead/IlxmQLqA0RZDeU1R6Teo7yuvwIiaEf9P1xicPib3CfonUU/0`
    wx.downloadFile({
      url: path,
      success (res) {
        if (res.statusCode === 200) {
          wx.saveFileToDisk({
            filePath: res.tempFilePath,
            success: function(res) {
             console.log(res) 
            },
            fail:function(res) {
              
             console.log(res) 
            }
          })
        }
      }
    })

z这样试试？