“I do not know” - this answer differentiates experienced professionals from the rest.
That single statement makes me trust the person I am working with. It also makes me value their guidance considerably more.
When you openly state that you do not know something, it makes people respect you far more.
As a Junior Developer, I felt significant pressure that I should know all the correct answers. I feared admitting the lack of knowledge would decrease my value among team members.
Years later, I remember a specific meeting with several stakeholders when I worked as a Solution Architect. Everyone claimed that we knew what we were doing and everything was great. Then, one executive asked for my confirmation. As an already experienced architect with an established position in the company, I stood up and said, “I do not know”. I will never forget that moment. All of a sudden, the room got quiet. After the initial shock, people started to openly share their concerns, as if my declaration gave them the approval to do so.
It does not matter if you are just starting your career or are an established expert in the field. Do not fear to share your lack of confidence, as that would only increase your authority.