Calibration helps, but it cannot fix the physical limits of a poor laptop panel. If your screen changes brightness or color when you move your head slightly, that usually means limited viewing angles and panel quality; calibration can make it more consistent, but not truly accurate across all conditions.

A better monitor will usually look better and be easier to edit on, even before calibration. However, without calibration, you still don’t have much assurance that the colors are accurate.

So:

• calibrating your current laptop can improve consistency,
• a better external monitor is likely a worthwhile upgrade for editing,
• the best setup is a better monitor plus calibration.

If you care about reliable color for editing or printing, use a hardware color meter/calibrator. That helps reduce unpleasant surprises and makes your display behave more predictably. Calibration is useful on either screen, but it won’t turn a low-end laptop display into a high-end editing monitor.