Yes you can do that on a form in the dynamic form rules section. You could either hide fields individually or you could do it by section. It just depends on how many of the fields the different sites had in common. Likely many of them are common fields. If the fields are unique to each site then sections can make more sense. By common fields I mean things like name, phone number, address, etc. Things you would have to fill out for each site no matter what.
You would just do a rule like this:
when [site name] is equal to "site 1" then show "section 1"
Be sure to select "Collapse the space when hiding fields" if it is there, not sure if it is for sections.
So the user would have to open the form and then select the site from the dropdown and then the section for that site would pop into existence for them.