Equivalent of constraint layout 0dp

Use Dimension.fillToConstraints:

A Dimension that spreads to match constraints. Links should be
specified from both sides corresponding to this dimension, in order
for this to work.

Add this line to your Text modifier:

width = Dimension.fillToConstraints

So it becomes:

Text(
    text = "This would be some text",
    style = TextStyle(
        color = Color.Black,
        fontSize = 18.sp,
    ),
    modifier = Modifier.constrainAs(title) {
        top.linkTo(parent.top)
        bottom.linkTo(parent.bottom)
        start.linkTo(checkbox.end)
        end.linkTo(icon.start)
        width = Dimension.fillToConstraints
    },
)