MaterialTheme

onSurfaceVariant

Surface() {  //light
  MyTextComposable()
}

Surface(color = MaterialTheme.colorScheme.primary) { // dark
  MyTextComposable()
}

@Composable
fun MyTextComposable() {
  CompositionLocalProvider(LocalContentColor provides MaterialTheme.colorScheme.onSurfaceVariant) {
     Text(...)
  }
}

LocalContentColor

onSurfaceVariant

import androidx.compose.foundation.layout.*
import androidx.compose.material3.*
import androidx.compose.runtime.Composable
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.unit.DpSize
import androidx.compose.ui.unit.dp
import androidx.compose.ui.window.*

fun main() = application {
    Window(
        onCloseRequest = ::exitApplication,
        state = WindowState(
            placement = WindowPlacement.Floating,
            position = WindowPosition.Aligned(alignment = Alignment.Center),
            size = DpSize(400.dp, 400.dp)
        )
    ) {
        Column(modifier = Modifier.fillMaxSize()) {
            MaterialTheme(colorScheme = lightColorScheme()) {
                MySurface(modifier = Modifier.fillMaxWidth().fillMaxHeight(0.5f))
            }
            MaterialTheme(colorScheme = darkColorScheme()) {
                MySurface(modifier = Modifier.fillMaxWidth().fillMaxHeight(1.0f))
            }
        }
    }
}

@Composable
fun MySurface(modifier: Modifier) {
    Surface(modifier = modifier) {
        Column(modifier = Modifier.fillMaxSize().padding(12.dp)) {
            Text(color = MaterialTheme.colorScheme.onSurface, text = "Text 1")
            Text(color = MaterialTheme.colorScheme.onSurfaceVariant, text = "Text 2")
        }
    }
}