For quality time you can take them somewhere special and make sure it’s just the two of you. Tell them how you truly feel about them and make sure they feel appreciated.
I have two answers. One: If your friend does not like getting attention and wants to be alone, just ask if they are ok and what is wrong. Text or call him/her that you are there for them and if they need help you can do that. Two: If your friend is a very social person you should ask them if they want to hang out, or (not in quarantine obviously) take them somewhere special. Ask them what is wrong. Be there for your friend.
