Go to microsoft/terminal ColorTool. Download the ColorTool release and extract the zip file.
Clone mbadolato/iTerm2-Color-Schemes. Copy the contents of the schemes folder into the ColorTool/schemes folder. Keep this page open so you can browse the screenshots to pick a scheme.
git clone https://github.com/mbadolato/iTerm2-Color-Schemes.gitRun the ColorTool utility with the name of the scheme file.
& 'C:\Program Files\ColorTool\ColorTool.exe' -b VibrantInk.itermcolorsWithout the -b the scheme is only set for the current window, not both the current window and default.
PowerShell will still screw up the screen background color. Right-click the title bar of the PowerShell, choose Defaults, choose the Colors tab, and set the Screen Background color manually, then hit OK. You can do the same for the current window using the Properties instead of Defaults.
For reference, the default PowerShell background is R: 1, G: 36, B: 86. That works well with VibrantInk.