Can you use Lightroom as a source for Photoshop EXISTING canvas

If the image has edits done in Lightroom Classic, those have to be accounted for.

If it’s a raw file with Lightroom Classic edits, here’s one way that I use all the time:

1. In Lightroom Classic, select the image in the Library module and choose the command Metadata > Save Metadata to File. (If in the Develop module, choose Photo > Save Metadata to File.) The purpose of this is to write Lightroom Classic edits to a sidecar file that can be picked up by Camera Raw in Photoshop.

2. (Mac only) Drag that selected photo file, and drop it into the Photoshop document window where you want it to be added. Camera Raw will open, which should show the Lightroom Classic edits. Just click Open. 

3. The image appears in the Photoshop document with an active transform rectangle. Reposition and resize as needed, or if it’s fine the way it is press the Enter or Return key. It’s now added as an embedded Smart Object.

If in step 2 you’re using Windows and the drag-and-drop solutions don’t work, you can do it the long way around, from inside Photoshop: Choose File > Place Embedded or File > Place Linked depending on which kind of Smart Object you want, select the file, and import it into the document as a new Smart Object layer. To locate the file more quickly for Photoshop import, in Lightroom Classic select the photo and choose Photo > Show in Explorer to have the file shown on the desktop in its folder.

If the source file in Lightroom Classic is in a format that doesn’t support Lightroom/Camera Raw edits in metadata (e.g. PNG, PSD), then you can’t use the steps above because any Lightroom Classic edits won’t be carried with the original. Instead, export a copy of the image and add that to the Photoshop document. 

Drag a photo App to App doesn't work in Windows (for me anyway), so I have the two 'documents' (new canvas & image to place) both open in separate Ps tabs, then drag the 'image to place' onto the 'canvas' image tab.

As far as i know, for now, unless someone knows about a plugin, is to put both applications side by side and drag the photo from Lightroom into the existing document in Photoshop.