To complement the colors #fa3d59 (vibrant pinkish-red) and #fffcfb (soft off-white) with another unusual yet fitting choice, I recommend adding #2d4b8c , a deep teal blue. This color adds a rich contrast and sophistication to the palette while still harmonizing beautifully with the bright pinkish-red and off-white.

Here is the updated color palette in JSON format:

json
{
  "palette_name": "Bold Balance",
  "colors": [
    {
      "name": "Vibrant Pinkish-Red",
      "hex_code": "
                            
                            #fa3d59
                        "
    },
    {
      "name": "Soft Off-White",
      "hex_code": "
                            
                            #fffcfb
                        "
    },
    {
      "name": "Deep Teal Blue",
      "hex_code": "
                            
                            #2d4b8c
                        "
    }
  ]
}

This palette creates a striking combination, where the vibrant pinkish-red brings energy, the soft off-white offers a gentle base, and the deep teal blue introduces depth and elegance, resulting in a bold and balanced color scheme. Would you like to explore more colors or specific themes?