https://developers.weixin.qq.com/miniprogram/dev/api/media/live/LivePlayerContext.requestFullScreen.html

############WXML
<live-player
            class="video"
            id="player_0"
            :src="rtmpurl"
            mode="live"
            autoplay
          >
</live-player>
<button bindtap='fullScreen'>full</button>

##############JS
fullScreen() {
  let ctx = wx.createLivePlayerContext('player_0')
  ctx.requestFullScreen({
    direction: 90,
   success() {
    console.log('full success')
   },
   fail() {
     console.log('full fail')
   }
  })
}
真机调试下，调用了全屏API完全没有反应，成功和失败回调都没有走