User wants to open project in a way that no one will be able to make changes in it, but will still be able to view it as read-only.

There is a feature called exclusive mode where a user who has access to the project can open it in exclusive mode. A user with Exclusive access to a project can open and edit a master copy of the project. Only one user at a time can have Exclusive access to a project. It will also show what users have it open and what mode they have it opened in.