Cannot change text font style and color using "§", but it can change in old UI.

In the old minecraft version, you can use §l or §c and other color code to change text font style and color, like §l can make text bold.

But in 1.21.62, when I using new UI, The new UI cannot show change of the text than have § code. But if you using old UI in your world, you can see change!