so yes because as the result is to export to images, it previews the result (which can be pixelated depending of the zoom).
You can see the canvas size (as a normal image software editor do) so for example if you need a model with a final resolution of let's say 1000px, the canvas should be at least 1000px and the 3d object should be scaled to reach the full canvas size.
Hey, sorry I had other things to handle I totally forgot. So here you go :
1) By selecting the canvas, you choose you page size. So here we can now display a model in a 1000px area. (Becareful with high res canvas, PixelOver uses realtime shaders so it can lag)
2) By selecting the model, you can scale with the tool (shift + a grabber to lock the ratio) or more precisely, in the left bottom panel properties, you can set manually the scale.
And that pretty much it, so yes to prevent pixel art look by selecting the layer you can set a mxaa but you already done that you said. Let me know if something unclear.