The leader was ill for two weeks and didn't go to work. I want to express my condolences to the leader. How can I express my condolences?

See how your relationship with him is. If you are good at ordinary times, go and have a look, bring some fruit or something, ask him how he is, talk about the company and wish him a speedy recovery. If you are not feeling well at ordinary times, you can call and send a message to say hello. If you are not familiar with it, some people may think that you are flattering or something. Of course, colleagues can also be invited to watch it together, and there will be no problem if there are many people.