As other suggested you can use a capture component to generate a cube map. This can be very high quality, and then saved as a texture. Then you would use the reflection vector as the coordinates for the Cubemap sample within your material.
This cubemap can also be used reused to make a fake refraction/transparency.
Here is an example material I made that uses a cubemap for both reflections and transparency. Notice the roughness is set to 1 yet it still appear to have a sharp reflection, and that the blend mode is opaque despite having the appearance of transparency.