BottomSheetSampleFragment.kt

class BottomSheetSampleFragment : BaseBottomSheetFragment() {

    override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
        val dialog = super.onCreateDialog(savedInstanceState) as BottomSheetDialog
        dialog.setOnShowListener {
            val bottomSheet =
                (it as BottomSheetDialog).findViewById<View>(com.google.android.material.R.id.design_bottom_sheet) as FrameLayout?
            val behavior = BottomSheetBehavior.from(bottomSheet!!)
            behavior.state = BottomSheetBehavior.STATE_EXPANDED
            behavior.isDraggable = false
        }

        return dialog
    }
    // Other stuffs
 }