I’m all about doing funky and random stuff, but the way accented colors are applied on modern pages in SharePoint Online has the distinct taste of fungi.
The colors scheme of the tenant has no bearing what so ever. It’s all calculated based on the site Title. If you however create a composed look and specify the accent colors, this will in fact overrule the random color.
A site named “a”
A site names “b”
I have not figured out the exact hashing formula to pick the color, but I have so far identified 10 colors in use – the same colors shown for sites listed on the SharePoint home page. From this list there’s a distinct tendency towards red – all very bright and alerting. How about a more calming color scheme?
If you don’t like any of these colors, or have a hard time finding a title to give you the right color, be sure to create and apply a composed look to your team or group site. Or go with old style pages where the randomness is no where to be seen – but where’s the fun in that?