How do I zoom in and refocus while filming?

Hi, I need to show a diagram in my new video (it’s in a triangle shape). so the client wants to focus on the whole image and then zoom in to just one part of the image, and the video then talks about that part. Q: Is there a way to have the whole sign or diagram in focus, than zoom in and focus on one part all in the one shot? How would you do this? Help! My shoot is less than 2 days time…
(Just to clarify, client wants a video made about waste reduction at festivals. There’s a diagram in the shape of a triangle starting wide at top with ‘reduce’, then under that ‘reuse’, ‘recycle’, recover’ and lastly ‘landfill’ which tapers to a point. They want this diagram used, and then zoom in as I said. How do you zoom in and retain focus? Are there cameras that do this automatically. My Canon 5D and 600D are shockingly noisy and terrible for this. Sorry just learning here!