Hi Community I am a Android Developer since 2 .5 Years using Kotlin, can anyone suggest me regarding learning kotlin in-depth as expertise

Have you checked this 👇 https://kt.academy/

What about "Kotlin Design Patterns and Best Practices"?

This is a good time to read Kotlin In Action (written by JetBrains team) and solve some Kotlin Challenges to practice problem solving using Kotlin (my repo)

Kotlin in Action but the EarlyAccess second Edition version: https://www.manning.com/books/kotlin-in-action-second-edition You'll get the ebook for the first edition for free, and the first 9 chapters of the second edition are also already done.