You can change the texture using load from url.
Otherwise, if you know the texture will be scaled up at run time every time, then scale the texture up before you import it into the editor.
Note, unless the texture scales up well, and most textures don't, you may still have the same issue, unless you create a texture of the target scale.
Also note, most, if not all textures scale down without quality loss.
I tried what you are saying before but it doesn't work, no matter what the source texture is, it always scales up which results in losing quality.