the problem is how you are importing your assets, these assets are rendered in pixel art resolutions, so its logic that if u import them like normal assets you'll get either blurry or low resolution images, if you are using godot i reccomand watching this video :
I'm not personally familiar with Roblox Studio, but in the engines I use, we typically use a "nine-patch rectangle" for scaling borders or screens. This type of rectangle expands only in specific areas while keeping the borders intact. For example, in the grid below, sections 2, 4, 6, and 8 can stretch, while 1, 3, 7, and 9 remain unchanged.