descargar modelo 3d

If you use english language maybe even people that don't know your language can understand what are you saying

Hey Daniel,

Please read the "Read this before submitting your post!" topic before you post something. The official language in Forum is English.
However, I'll help you out this time, it would probably translate into something like this:
"I downloaded a 3D model but when I want to open it in 3 d max i get too small what I can do to fix it"

All the best,
Eduardas

In 3ds Max you can use the scale tool to increase the size or go the the Customise menu and select Units Setup to change the System Units Setup.