Text Alignment in Jetpack compose

One alternative is measuring width of prefix texts and passing maximum width to ListItem

val density = LocalDensity.current

val textMeasurer = rememberTextMeasurer()

val prefixWidth by remember(prefix, prefix.size) {
    derivedStateOf {
        with(density) {
            prefix.maxOf { text ->
                textMeasurer.measure(text).size.width
            }.toDp()
        }
    }
}

Demo

@Preview
@Composable
private fun TextAlignTest() {

    val prefix = listOf("1.", "2.", "3.", "4.", "5.", "6.", "7.", "8.", "9.", "10.")
    val description = listOf(
        "First",
        "Second",
        "Third",
        "Fourth",
        "Fifth",
        "Sixth",
        "Seventh",
        "Eighth",
        "Ninth",
        "Tenth"
    )


val density = LocalDensity.current

val textMeasurer = rememberTextMeasurer()

val prefixWidth by remember(prefix, prefix.size) {
    derivedStateOf {
        with(density) {
            prefix.maxOf { text ->
                textMeasurer.measure(text).size.width
            }.toDp()
        }
    }
}

    Column(
        modifier = Modifier.padding(16.dp)
    ) {
        prefix.forEachIndexed { index, prefix ->
            ListItem(
                prefixWidth = prefixWidth,
                prefix = prefix,
                description = description[index]
            )
        }
    }
}

@Composable
fun ListItem(
    prefixWidth: Dp,
    prefix: String,
    description: String
) {
    Row {
        Text(modifier = Modifier.width(prefixWidth).border(1.dp, Color.Red), text = prefix)
        Spacer(Modifier.width(8.dp))
        Text(description)
    }
}

This is your code

@Preview(showBackground = true, showSystemUi = true)
@Composable
fun SampleSOF(){
    Column {
        Row{
            Text(text = "1.")
            Text(text = " First")
        }
        Row{
            Text(text = "10.")
            Text(text = " Tenth")
        }
    }
}

Here is one way to solve it

@Preview(showBackground = true, showSystemUi = true)
@Composable
fun SampleSOF(){
    Row{
        Column {
            Text(text = "1.")
            Text(text = "10.")
        }
        Column {
            Text(text = " First")
            Text(text = " Tenth")
        }
    }
    Row{


    }
}

Below Code will work when space width equal to the character width

@Preview(showBackground = true, showSystemUi = true)
@Composable
fun SampleSOF(){
    Column {
        Row{
            Text(text = appendSpacesToString("1.",5))
            Text(text = " First")
        }
        Row{
            Text(text = appendSpacesToString("10.",5))
            Text(text = " Tenth")
        }
    }
}
fun appendSpacesToString(content : String, lenght : Int) : String {
    var contentLenght = content.length
    var newContent = content
    if(lenght > contentLenght){
        var nl : Int = lenght - contentLenght;
        while (nl > 0){
            newContent += " "
            nl--
        }
    }
    return newContent
}

You can maintain fixed width like this also

@Preview(showBackground = true, showSystemUi = true)
@Composable
fun SampleSOF(){
    Column {
        Row{
            Text(text = "1.",modifier = Modifier.width(30.dp))
            Text(text = " First")
        }
        Row{
            Text(text = "10.",modifier = Modifier.width(30.dp))
            Text(text = " Tenth")
        }
    }
}

@Composable
fun test() {
    val list1 = listOf<String>("1","2","3","4","5","6","7","8","9","10")
    val list2 = listOf<String>("one","two","three","four","five","six","seven","eight","nine","ten")

    LazyColumn(horizontalAlignment = Alignment.Start){
        items(10){
            Row( modifier = Modifier.fillMaxWidth()) {
                Text(text = list1[it],Modifier.fillMaxWidth(.2f))
                Text(text = list2[it])
            }
        }
    }
}