@burnout426 Good tip about standalone installation!
I realized that I also have Opera installed on my laptop running Windows 10. I clicked the three dots at the bottom left corner and found that somehow it already had three workspaces named Workspace 1, Workspace 2, and Smart shopping. I didn't put them there. But Workspace 1 and Workspace 2 do bring up different sets of tabs (one with two tabs, the other with none). I was able to add a Workspace 3. And right-clicking a tab does bring up "Move tab to workspace".
I searched Settings and Help for "profile" and found two things, one of them helpful: Crashes and issues. I think I can take it from here. Thanks again!