Hello, lets see what the resolution of the imported texture is. Open Windows Explorer and check out the texture resolution. I would imagine your preferred resolution would be 2048 x 2048 or 4096x4096.

Verify the imported texture is the same image.
- Open the Content folder.
- Find the texture maps.
- Double click on them, one at a time.
- then verify the resolution of the imported texture.
If the image is smaller than 1024 x 1024 then I would assume you would just need to export a higher resolution of the preferred texture from your source DCC. Make sure your Albedo, Normal, AO, and etc textures are all a high resolution.
This is a simple material set up to verify your albedo and normal map.

