We don't have enough information to know exactly who Karen is. She could be an ordinary person, a student, a teacher, or just someone who likes to read stories.
I'm not entirely sure as it could be a rather niche or specific visual novel. It might be about different classes or groups within a school setting in a fictional story presented in a visual novel format.
Given only 'dateline karen read story', Karen's identity remains a mystery. She might be a staff member at Dateline who was reading a story for work purposes. Or she could be a person who was interviewed by Dateline and was reading a story during the interview, or she could be an ordinary person whose story - reading experience is being highlighted in relation to Dateline.
It might be available on some specialized visual novel platforms. You could start by checking out well - known platforms like Steam if it's been released there. Some indie visual novel distribution sites might also have it.
I'm not sure specifically as I haven't read this particular 'zettai ni yatte wa ikenai isekai novel'. It could be about various things common in isekai novels like a protagonist being transported to another world but with some kind of moral or rule that they must not do certain actions (as the 'zettai ni yatte wa ikenai' part might imply).
It's hard to say for sure. 'Karen' could be a blend of real incidents and creative imagination. Sometimes, such stories take real-life inspirations but are embellished for entertainment value.