One of the most useful design-related tools I've found is this color picker which generates complimentary colors for you based on model of your choice (triadic, analogous, etc.):
I always struggled with picking complimentary colors and found this worked a lot better than most of the pre-defined color palette suggestions out there.
https://www.sessions.edu/color-calculator/
I always struggled with picking complimentary colors and found this worked a lot better than most of the pre-defined color palette suggestions out there.