You can get page content using the Notion API, but it returns content as block objects, not as plain text or markdown. You'll need to:

1. Call the Retrieve block children endpoint
2. Manually parse each block type and convert it to your desired format.

Alternative: If you need markdown output instead of parsing blocks manually, I built an API service that handles the conversion automatically: Mark2Notion. It extracts Notion pages as clean markdown with proper formatting, tables, lists, etc.

Docs: https://docs.mark2notion.com/api-reference/notion-to-markdown