Add, remove or view a SharePoint site theme on your tenant.
Got to https://developer.microsoft.com/en-us/fabric#/styles/themegenerator
Set your colors. Select PowerShell as your Output.
Replace value for $themepalette variable in SPOSiteThemeCF.ps1
$themepalette = @{
"themePrimary" = "#e20074" ;
"themeLighterAlt" = "#fef4f9" ;
"themeLighter" = "#fbd2e7" ;
"themeLight" = "#f7add3" ;
"themeTertiary" = "#ee5fa9" ;
"themeSecondary" = "#e61c84" ;
"themeDarkAlt" = "#cc006a" ;
"themeDark" = "#ac0059" ;
"themeDarker" = "#7f0042" ;
"neutralLighterAlt" = "#f8f8f8" ;
"neutralLighter" = "#f4f4f4" ;
"neutralLight" = "#eaeaea" ;
"neutralQuaternaryAlt" = "#dadada" ;
"neutralQuaternary" = "#d0d0d0" ;
"neutralTertiaryAlt" = "#c8c8c8" ;
"neutralTertiary" = "#c2c2c2" ;
"neutralSecondary" = "#858585" ;
"neutralPrimaryAlt" = "#4b4b4b" ;
"neutralPrimary" = "#333" ;
"neutralDark" = "#272727" ;
"black" = "#1d1d1d" ;
"white" = "#fff" ;
"primaryText" = "#333" ;
}