If a smartphone supports retina, can zooming in a mobile browser make the picture fuzzy?

Question

Web development

Considering a spherical horse in a vacuum - pure theory.
Let's say we have a website optimally designed for mobile browsers with a pixel ratio above 1 (1.5; 2; 3; 4 ...). It works correctly with pictures in both design elements and content.
Let the visitor open the site on a smartphone (as an option, iPhone 5, pixel ratio 2). He saw an interesting picture on the page and wants to enlarge it (standard zoom gesture).
What can a visitor expect when zooming in on a picture in terms of clarity? Does it get worse, does it persist? To what degree of scaling?
The question arose when visiting the Apple website from their own smartphone and scaling the picture with the product. When enlarged, it loses clarity.

Answer 1

1. Open ANY image, ANY size, ANY format, in ANY program that can display images.
2. Select 100% scale.
3. Start "zooming in" more.
4. Yes, the image is no longer so cool and nothing can be done about it. Improving and preserving it in its original form will not work.