What is similar? Does it need to be a band anime? Does it require social anxiety characters? Just cute girls doing cute things (CGDCT) in general? Have yuri elements?

• slice of life (SOL) with characters playing in a band: K-ON! (band aspect is secondary)
• SOL with anxious main character: Hitori Bocchi no Marumaru Seikatsu
• general SOL/CGDCT classics: Lucky Star, Nichijou, Azumanga Daioh
• more modern SOL/CGDCT: Kiniro Mosaic, Gochuumon wa Usagi desuka?
• SOL with yuri: Hidamari Sketch (moderate, also a classic), Yuyushiki (lots)

edit: I personally don't think that Bocchi the Rock! is super laid back, but if you compare it to action shows it obviously is. If you really want to go the laid back route you can look into the genre Iyashikei ("healing type") with anime such as Non Non Biyori, Yuru Camp (still have to watch this one so can't verify personally but is very popular) and Yokohama Kaidaishi Kikou (absolute classic).