private const val TEXT_ORIGINAL = "XTest"
private const val TEXT_TRANSFORMED = "Test"

val visualTransformation = object : VisualTransformation {
    val offsetMapping = object : OffsetMapping {
        override fun originalToTransformed(offset: Int) = (offset - 1).coerceAtLeast(0)
        override fun transformedToOriginal(offset: Int) = offset + 1
    }
    override fun filter(text: AnnotatedString) = TransformedText(
        text = AnnotatedString(TEXT_TRANSFORMED),
        offsetMapping = offsetMapping,
    )
}

fun main() = singleWindowApplication {
    Box(
        modifier = Modifier.padding(8.dp),
    ) {
        BasicTextField(
            value = TEXT_ORIGINAL,
            onValueChange = {},
            textStyle = TextStyle(fontSize = 52.sp),
            visualTransformation = visualTransformation,
            modifier = Modifier
                .border(1.dp, Color.Black)
                .padding(4.dp)
        )
    }
}