Complete code for matchParentSize modifier that is used in the advanced jetpack compose modifier post of my website named jetpackcomposeworld.com

matchparentsizemodifier.kt

@Composable
fun MatchParentSizeModifier(modifier: Modifier) {
    Box {
        Spacer(
            modifier = Modifier
                .matchParentSize()
                .background(Color.Gray)
        )
        WebsiteNameShower()
    }
}

@Composable
fun WebsiteNameShower() {
    Text(
        text = "Jetpack Compose World",
        modifier = Modifier
            .padding(16.dp)
            .background(color = Color.Green),
        fontSize = 32.sp,
        fontStyle = FontStyle.Italic,
        textDecoration = TextDecoration.Underline
    )
}