Anecdotal:
I get very anxious from marijuana. Somewhat manic even. I hate the feeling. I’m generally not a stranger to anxiety in life.
I don’t get anxious from LSD. I _have_ felt anxiety on it that I had been repressing, felt it kind of wash over, but it was ... useful. Not difficult. I knew what it was. I wasn’t lost in it. It wasn’t like being swallowed by the uncomfortable anxiety from marijuana that kind of takes over or drives.
And, well, I think a low LSD dose actually helped me resolve a thread of anxiety I had had since I was a child. An permanent and obsessive safety-seeking walk down an endless tree of decisions and judgement. Kind of a background thread. I kind of ... found it again? Had forgotten it was there? And could revisit it and ... know to stop. “Just stop judging”, i.e. judging the situation. And it felt like I could. It still feels like something was let go of. But idk!; Anecdotal!
There are studies that show that when starting with low doses, then very few people get anxious. Other studies show that when people _do_ get anxious, there are still lasting benefits to well being. As I understand it. There’s a decent seeming summary of this on http://tripsafe.org