Perhaps in answer to my own question. There is no need for a add on tele convertor.
I noticed when i did a web search that the sony has a built in Smart Telecon option. What i could not find out though was if this has set zoom magnifications, or whether you just use the zoom to create the crop you are looking for up to 2.3x?
Secondly, does this create a zoom box within the main view, or does it actually zoom in on the image?
Does this zoom mode operate when in the 'macro' setting?
Lastly, i read that this does not operate in RAW, is this correct?
With 42mp, and almost 2x zoom would be close to 21mp at 70mm. This would be great, and I hope that it is allowed in RAW if the first versions were not. I suppose one could just shoot it at 35mm in raw and then crop in post, but I always prefer to compose roughly close to the final image size than to make a 2x crop in post.
I also wish that they had the same paint work as the a7rii, and not the semi-gloss that they are using.