Resolution quality and FPS for API users

Hello, I'm using the HeyGen API and I need to get the best quality talking head videos possible. I'm using Eleven Labs to good effect for TTS and SSML etc. But, using the free plan API is producing poor quality videos. Would going to the pro plan and making use of 4k video be the best option? Also, is there no option for upting the FPS to 60fps?

Thanks, Luke