Welcome to forum. I'm glad that you're reaching out for ideas on how to support a friend / be a supportive friend.
The idea of 'support' comes in different forms, and support will look different from person to person. You may perhaps start with R U OK and headspace resources?
I would recommend sharing the Beyond Blue hotline 1300 22 4636, or the online chat / forum links where they can discuss their concerns with confidentiality.
Hope these resources would give you some ideas for support.
There would be other threads on the forum around 'staying well' and providing support for friends too which may give you some further thoughts.
Feel free to stick around the forum, comment/update whenever !
Stay well. Warm regards, CP