LinkedIn is a social media platform for Business professionals and other professionals used for Hiring and Getting jobs, etc. So it can provide a wealth of information about many people which can be trusted to a very high/great extent (But not always. Remember Fake Profiles do exist here as well).
Lets say you want to view a profile. Search for it. Once you get it, right click on the image - Profile picture or Banner picture - (if any) and open in a new tab. From here you can easily conduct Reverse Image Search .
LinkedIn also has a place for Contacts of that person which mostly/generally include phone number, email Id, Social Media handles, Birthdays, Websites (Portfolios and others), etc. These can be of great help.
You can go to the posts, history, etc. of the user (whose information you want). You can also view the Education, Experience, People/Influencers (he/she follows). In all these you can click on the respective icons of Schools (in Education), Companies (in Experience) and get to know about schools and companies. These help alot in gathering information.