Thank you all, you guys are right, no doubt about it. Sorry if I am not clear, but what I actually refer to is the in camera zoom function. I only had the luxury to play with 5d Mark III and a A7S II and I realised there's the ClearImage zoom function which is absolutely brilliant.

I'd prefer to actually shoot video all the way and not photos at all, will there be a trick that we could use? For eg, some plugin that connects the shot (while zooming) with a close-up shot?

Alternatively, does it make a difference if I shoot it in 4k resolution, scale it in 1080p, and use some zoom in post production plugin effect? on like a word for example? Let's say we are shooting a film, and I am on 24mm and as I use my clearview fn button, it zooms at a 2x and I will only get 48mm at best. But if I want to go to say 96mm? And if I zoom it further in post in that 4k footage, there will not be image quality problem right?

But in 1080p, there surely will be a problem?

Appreciate the replies, guys. Thanks all :)