All Airtable rows currently have a fixed height of a single line. To expand a single row at a time, you can press space with any cell in the row selected.
You can also expand an individual text cell by clicking the expand button inside the cell, or by pressing shift+space with an individual cell selected. You can then use the arrow keys to quickly move around between different cells.
Finally, our gallery view offers a card-based layout which supports multi-line text fields.