Preserving image quality when using a sprite at different scales

Hey all - sorry if the question is obscure; I'm still very new to Unity. Any help on this is very appreciated!

I've been having trouble with image sizing on a 2d card game I'm building. The cards are built using scriptable objects and saved as prefabs (with a source image of the card attached). The game has a deck draft phase, where the user will be presented with card options, and a battle phase, where the user battles enemies with their deck.

My problem is, if I export my card at a larger size (600x900) and attach that to the prefab, the quality is preserved during the deck draft phase; but during the battle phase, I have to scale the card down in Unity to fit into the player's hand - rendering the cards blurry and tacky. If, however, I export the card at a smaller size, the cards look great during the battle phase - but are equally blurry during the deck draft due to upscaling.

I've thought about attaching multiple versions of the same card's picture (at different sizes) to the prefab, but that doesn't seem very elegant - and will quickly become an unsustainable problem if I choose to add more scenes that need the card at different qualities.