Currently, we do not support this functionality. I have logged a feature request on your behalf in our public feedback portal. I am sending you a link to the item: Entry: Provide an option to change the cursor(caret) color. You could vote for the implementation of the item and subscribe for it, in order to get notified by email for any status updates.
Set the cursor color only on the Android platform:
I tested several options and succeeded to change the cursor color, but only on the Android platform. I am sending you an example project to see how the desired behavior is achieved. Test this on your side and see if this approach will work for you. On WinUI, there isn't such property for the native TextBlock control. On iOS and Mac the tint color does not apply to the native element.