free transform an image with perspective

I don't fully understand "get anchor points on an image". By "image" do you mean a raster image?

For placed raster images, an easy workaround is to select the image and `Object > Envelope Distort > Make with Mesh` - 1 row 1 column. Then you can use the Free Transform Tool with the Persepctive distort.

Any native vector object or group will work the same with the perspective distort function of the Free Transform Tool.

You cannot do this directly, but you may try this workaround.