It's fun to look up live performances of anime music on YouTube, because Japan takes this stuff very seriously but also does a lot of interesting stuff with this sort of thing. If you want just standard orchestral renditions, you can find that...but if you want to hear your favorite anime theme played by an orchestra and a marching band as it marches through a stadium, you can find that, too!
Here's a concert performance of Joe Hisaishi's main themes from Laputa: Castle in the Sky. This one is somewhere in the middle in terms of how flashy it is. I love this music and I'd love to hear one of these concerts one day!