I purchased a larger bathroom vanity. The floor drain is 4-5" left of center of my opening in the back of the piece. I am unwilling to cut a hole in the bottom of the vanity, since it is a solid wood furniture piece. I only have 4" clearance under the vanity.
Could I run a drain line using flexible pvc, and a 90 elbow?

It probably isn't code in a locale. You can ask your town inspector.
Why can't you go out the back, down the wall, and back under the cabinet with elbows and a tiny bit of slope for that small number of inches front to back, side to side, and even under the vanity? 4" is plenty of height.

Have you tried just rotating your trap one quarter trun, that should move the end drain over about what you need. Why do you need a flx PVC, you could use two 90 elbows on a rigid PVC drain pipe.

Thanks, That is what I first tried, but it left a larger than desired gap between the wall and vanity. The elbow on the floor drain comes out in front of the baseboard, adding the width of the ridged pvc, left me unable to push the vanity closer

I tried that but it left too big a gap to the wall. I think I will cut down my baseboard in order to push my vanity closer to the wall. Thanks