MainActivity.kt

Scaffold(
        topBar = {
            if (searchWidgetState == SearchWidgetState.OPENED) {
                SearchAppBar()
            } else {
                TopAppBar(
                    //...
                    actions = {
                        IconButton(onClick = { searchWidgetState = SearchWidgetState.OPENED }) {
                            Icon(
                                imageVector = Icons.Rounded.Search,
                                contentDescription = "",
                                tint = Color.White,
                            )
                        }
                    },
                )
            }
        },
    )