animateAsState.kt

@Composable
fun AnimationLayout() {

    var state by remember { mutableStateOf(false) }

    val startColor = Color.Blue

    val endColor = Color.Green

    val backgroundColor by animateColorAsState(
        if (state) endColor else startColor 
    )

    Column(
        modifier = Modifier.fillMaxSize().background(backgroundColor),
        verticalArrangement = Arrangement.Center
    ) {
        AnimationButtons(onValueChanged = { currState ->
            state = currState
        }, state = state)
    }
}

@Composable
fun AnimationButton(onValueChanged: (Boolean) -> Unit, state: Boolean) {
        Button(
            onClick = { onValueChanged(!state) },
            modifier = Modifier.height(50.dp).width(100.dp).padding(top = 10.dp),
            content = {
                Text(text = "Animate", color = Color.White)
            })
}