Add search criteria in the Finder in Catalina

I have a MacBook Pro (Retina, 15 inches, mid-2015) with a 2.8 GHz Intel quad core i7 processor, now running macOS Catalina 10.15.3. Before the upgrade, I could do a search as follows. Press ⌘ + F to open a Finder window; select what I want to search (this Mac, recent files, etc); press the Plus Sign to add criteria (such as extension, title, type of file, etc). After the upgrade, there is no Plus Sign. All I can do is search all occurrences of whatever I type. How do I add search criteria like I did before?