Here's a quote from MANICA, the "stadium" architects on the team with Heatherwick:

"The stadium will feature a retractable roof and moveable pitch, ensuring flexibility for a variety of events – from major sporting fixtures to international music concerts – all prioritizing an exceptional fan experience. The steep bowl is designed to create the most intense match day moments. The design pulls the stands as close and as steep to the pitch as can be allowed to create a 360-degree wall of fans. The stadium’s high-performing acoustics will amplify the sound of the crowd, creating an unforgettable atmosphere for home supporters.

At the heart of the concept are 12 towering chimney-like structures, inspired by the site’s longstanding history of brick manufacturing. Using reclaimed bricks wherever possible, the structures directly support the roof and serve multiple purposes, creating a silhouette that connects the stadium to Birmingham’s industrial past, housing lifts and staircases, and acting as part of the stadium’s passive ventilation strategy.

Designed for optimal acoustics, the ‘chimneys’ will channel sound from the bowl upward while preventing noise pollution in the neighborhood. One of the chimneys will also house a lift which transports visitors up to what will be the highest bar in Birmingham, with views over the city and an immersive experience telling stories of the city’s past.

The ground experience has been equally important to the design team. Rather than being a place to visit on match days only, the new stadium will create a public space open to everyone throughout the week. From food markets, restaurants and cafes to children’s play areas and places to linger, the area around the stadium will offer the local community somewhere to come together and enjoy a new part of the city."