I don't know your exact situation. So I can only speak for myself:
The therapist has almost no power over me. I am the one in control. I say what we discuss, when we discuss it and if we stop talking about it. The only boundary is time, and even there my therapists are willing to work with me. It took me a while to open up with my first T, I think I just had to get through that uncomfortable feeling once or twice, then it was gone.
As for things like hospitalization, showing you are not a threat and so on: if you see your T regularly and open up, they get to know you and they will be able to judge whether your responses might indicate you needing more care. But at least my Ts will never go against my will, it would be a conversation where maybe I decide to go to the hospital, it's never forced upon me. This in turn lets me trust and open up more, since we're a team working together on my mental health.