Btw, if you have a decent internet connection, you could give
GeForce Now a try, which I believe you can use for BG3 if you have a Steam key. I think the basic version is free, though quality is restricted and you can only play for an hour at a time. But still, you could at least see if it seems better than your old PC and if it's worth paying for a monthly subscription which isn't cheap but certainly costs less than buying a new gaming rig!