Are you using an HDRI with your render, or is it the default one? There are a lot of really high quality HDRI's out there that are great for rendering character portraits. It looks like you don't have any lights in your scene so its using the camera headlamp to render which isn't very good, I would suggest adding some spotlights to your scene to make her pop and create contrast.
This is how I set up my portrait scenes, I use a key light coming from the left and highlight the right with my rim light, and pair it with an HDRI
This is the result of this lighting setup
Also make sure your rendering devices are setup and you have OptiX prime acceleration on.
Setup your optimization tab like mine
Setup your filtering like mine as well
These are the render settings I use for most of my renders. 98% converged is usually pretty good for a game render considering you need to balance time and efficiency.
The light sets i'm using can be found here VVVV They also come with tone mapping presets.
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If you have any questions i'll gladly help you out
Also I like the character!