For casual viewing, the Retina display is generally fine if the colors look good to you. If you only care about seeing photos on your own screen, your personal judgment is usually enough.

If you want reliable color for editing and especially for prints, you should calibrate the display. All monitors vary somewhat, and calibration should be repeated periodically as the screen ages and changes.

A simple first step is to use macOS’s built-in display calibration tool in Display settings/preferences and evaluate the result. If you need more accurate, repeatable color, use a hardware calibration device such as a Spyder-type monitor calibrator.

For print matching, calibration is only one part of color management—you’ll also need a proper color-managed workflow so screen and print are more consistent.