Upscale first, then do your final sharpening.

That’s the standard workflow because sharpening is usually best as the last step. If you sharpen before enlarging, the resize process can soften or stretch that sharpening, so you may need to sharpen again anyway. Upsizing inherently adds some blur, depending on the interpolation method and how much enlargement you apply, so sharpening after resizing is generally more efficient and produces cleaner results.

Some resizing algorithms include a bit of built-in sharpening, and very large resizes can involve more complex processing, but the general rule still holds: resize to the target dimensions first, then apply output sharpening once.

If you want a specific creative look, pre-sharpening can sometimes be used intentionally, but for best technical quality and fewer artifacts, resize first and sharpen last.