No idea what you searched. But you would know that 20% is the way to go for what youre looking for.
Window tint options
https://x3.xbimmers.com/forums/showthread.php?t=1600482
Front windows tinted to match.
https://x3.xbimmers.com/forums/showthread.php?t=1511701
Factory tint + front tint
https://x3.xbimmers.com/forums/showthread.php?t=1502221
Good luck.