Via Google Translate:
How to print only part of my drawing if I want this part to be printed bigger because I want to see the details of this part of my choice.
1. Create a separate layer for a "page space"
2. On the new layer, draw a rectangle around the detail you want to print. Make it proportional to the page size defined in the Drawing Preferences.
3. Hide all layers except for the "page space" layer
4. Switch to the "Print Preview" view
5. Click the "Fit to page" icon. The rectangle drawn above will zoom to fit the extent of the page.
6. Turn on the other layers to be printed.
7. Print the resulting view.
You might get some artifacts on the page margins.
It is possible to print to scale, but it would be necessary to size the rectangle appropriately.