I played around with this for a long time and came up with a compromise to getting things the way I wanted. You can change color of title bars and borders, but you can't change the pukey gray TOOLBAR color in explorer and some other Windows apps. Early on in Windows 11, I was able to change this toolbar color using a theme but changes were made to GUI that now prevents it.
I like light mode but found that "show accent color on start and taskbar' was grayed out. It is because Windows has to be in dark mode for it to be available. Here's what I did to use these options in light mode. I think you may have already figured this out, but I'm including it again so anyone else seeing this thread can keep everything in context.
go to settings-personalization- colors.
under 'choose your mode', change it to dark mode (this is temporary and it un-grays the option.)
Change 'show accent color on start and taskbar' to ON and change 'show accent color on title bar and windows borders' to ON.
scroll back up to 'choose your mode' change it to CUSTOM
set 'choose your windows default mode' to DARK
set 'choose your app mode' to LIGHT
I then used Winaerotweaker portable under "Appearance" section and changed the color of my inactive title bars. (The active title bars use my accent color)
Under "advanced appearance settings" I adjusted the scrollbar and windows border width as they were too narrow for my liking.
I took it one step further using WinTools Classic Color Panel. Wintools has a great explanation section that tells you what each value does.
I tweaked my hot tracking color because I couldn't see much difference in default navy link color and black. I made it a dark maroon. You can see the result in this forum’s page below. My active Window is Firefox in this screenshot.
I changed my highlight color to one matching my desktop. I couldn't handle that stark white background so by changing the color for “window” I gave it a little gray tint that made everything easier on the eyes. At this point I NEARLY have it like I want but intend to keep playing with it as I have time.
Maybe this will help someone who wants to get a little more personal with personalization.