How to control how large the image size when PS opens it

That would mean that you will have to downsize the image. A raw file contains only one color per pixel. When the image is opened in Photoshop it is ‘demosaiced’ and becomes an RGB file with three colors per pixel. That means that it is completely normal and to be expected that your image in Photoshop is three times as large (could even be more if the raw file is compressed). If you set Photoshop to open the raw file in 16 bits per color, this doubles again.