If you convert from 8bit color to 16bit color you will not recover lost color or gain color. You will be able to edit in 16bit color gradient will work better less banding and you can place and copy in 16bit color image without loosing color information.
If you convert from 16bit color to 8bit color you loose color information. Most devices only support 8bit color. 16bit colors will be rendered as 8bit color.
You can of course reprocess your RAW file and convert the raw mosaic image into a 16bit RGB image in any color space you like ProphotoRGB AdobeRGB and sRGB.
If you had opened your RAW file as a smart Object you most likely can use image mode to convert the document to 16Bit color then Open the RAW Smart Object in ACR and change the workflow option to 16bit color to recover the color information lost in the first conversion when you click OK in ACR. The Photoshop document needs to be in 16bit color