False, I for sure have realtime collaberated with people on the same doc. I thought maybe it might be on a individual block level, but then from the Notion docs https://www.notion.so/help/collaborate-within-a-workspace,

"You can edit the same block as someone else at the same time. Unlike other document software, content is not locked if someone else is making changes to it. The most recent change will be reflected on the page."