attivare i partbody di un file scaricato

(thanks for translating your question to English, so dummies like me can understand)

Here are 4 different ways to see all the Bodies in your CATIA model:

1. use VIEW + TREE EXPANSION + EXPAND ALL LEVLES. This will show you everything in the tree, so you can find all the Bodies

2. use TOOLS + PARAMETERIZATION ANAYLYSIS and set Type = BODIES. This will give you a list of all the Bodies and Geom Sets

3. use EDIT + SEARCH and set Type = BODY. This will give you a list of all the Bodies

4. (the easiest way) click the little down arrow in the DEFINE IN WORKSET box to see a list of all the Bodies and Sets (but it doesn't expand the tree to show you where they are) see attached picture

(sorry I didn't translate this to Italian - too long)

That's a different question; "Would I like to see the profiles of my object?
how it was designed / built"

Based on the image you recently attached, you cannot see the features of how that Part Body was built because it is an isolated solid. The little red zig-zag symbol on the solid icon means this Body has been isolated (features deleted), making the feature a "dumb solid" with no history of how it was made.