Esto es lo que hice para obtener el mismo ancho que el campo de texto: copiar y modificar la respuesta de Gabriele.

 var expanded by remember { mutableStateOf(false) } val suggestions = listOf("Item1","Item2","Item3") var selectedText by remember { mutableStateOf("") } var dropDownWidth by remember { mutableStateOf(0) } val icon = if (expanded) Icons.Filled..... else Icons.Filled.ArrowDropDown Column() { OutlinedTextField( value = selectedText, onValueChange = { selectedText = it }, modifier = Modifier.fillMaxWidth() .onSizeChanged { dropDownWidth = it.width }, label = {Text("Label")}, trailingIcon = { Icon(icon,"contentDescription", Modifier.clickable { expanded = !expanded }) } ) DropdownMenu( expanded = expanded, onDismissRequest = { expanded = false }, modifier = Modifier .width(with(LocalDensity.current){dropDownWidth.toDp()}) ) { suggestions.forEach { label -> DropdownMenuItem(onClick = { selectedText = label }) { Text(text = label) } } } }