I highly recommend checking out the Rode VideoMicro compact on-camera microphone. Some key benefits:

• Very compact and lightweight, perfect for the small Sony a6600
• Provides a significant upgrade in audio quality compared to the built-in camera mic
• Plugs directly into the camera's mic input, no batteries required
• Includes a shock mount and furry windshield for reducing handling noise and wind noise
• Affordable price point around $60

I've been using the VideoMicro on my a6600 for vlogging and it works great. The audio is clear and it's very easy to use.

I use DJI MIC 2, and it works well all the time.