The classic starter combination.
Read three values off the grid: indigo 500 is #3F51B5, indigo 700 is #303F9F, and pink A200 is #FF4081. Assign them as colorPrimary #3F51B5, colorPrimaryDark #303F9F, colorAccent #FF4081, and you've rebuilt the starter theme that shipped with Android Studio project templates for years.
The combination works for teachable reasons. The 700 sits two visible steps below the 500 in the same column, so bar and status bar read as one material under different light. The pink accent sits far from indigo on the hue wheel, so a floating action button in #FF4081 can't be mistaken for chrome. Swap in teal 500 #009688 with teal 700 #00796B and an orange accent, and the same three-slot logic holds.
Before you click, set the copy format. HEX gives #3F51B5, RGB gives rgb(63, 81, 181), MUI gives indigo[500] or pink.A200 for code that imports colors from @mui/material/colors, and CSS variable gives a ready line like --md-indigo-500: #3F51B5;. Picking the format your codebase uses saves a round of find and replace later.