My Excel row is locked at height of 409.5 and I want to increase the size

1. Create a row below the row you want taller than 409.5

2. Select cell of top row, and cell of bottom row

3. Click arrow next to the Merge & Center button in the Alignment section of the Home tab on the ribbon

4. Click Merge Cells

You can repeat this process multiple times if two cells worth of height isn’t enough.

Note that Merge & Centre isn’t available for a table, only a standard worksheet.