I have a photograph named
A.jpg. I have to send it to some other person and I dont want him to zoom it more than 30%.
Is there any such option? I am ready to change my extension of the photograph also, to e.g.
A.pdf or something.
This isn't possible, because computers do not work like this. Once someone has the data, they can generally do whatever they want with it. Now, it is certainly the case that big media companies would like to cripple computers so this isn't true, by introducing DRM — "digital rights management", where the "rights" are really "restrictions". This is used for streaming movies and music, and sometimes games. You could theoretically send your photo using some program which includes this kind of software, but generally it is a) expensive, b) difficult to use, and c) not actually very effective. And that would even presume something exists tailored to your photo display task — and I don't think it does.
So, in that case, the answer here is simply to not send the full-resolution photo to the other person. Simply use Photoshop or some other software to rescale the image to be much smaller. I don't know exactly what you mean by "zoom it more than 30%", but basically, the strategy would be to make it so that zooming in all the way to 1:1 would only show the level of detail you want.