maxFontSizeMultiplier works differently between iOS and Android

Description

• maxFontSizeMultiplier affects the fontSize on both Android and iOS.
• When font scaling is set to a value higher than maxFontSizeMultiplier, both Android and iOS clamp the fontSize value
• When it comes to lineHeight, it acts differently. iOS clamps the value while Android ignores the maxFontSizeMultiplier for lineHeight

Please see the screenshots for a side-by-side comparison

Steps to reproduce

1. Install he reproducer app with yarn android and yarn ios
2. Take a screenshot of the app so you can compare later
3. Increase the font scaling. You can either use the settings app, or cmd option + on iOS simulator, and adb shell settings put system font_scale <value> on Android
4. Take another screenshot and compare those two

React Native Version

0.85.2

Affected Platforms

Runtime - iOS, Runtime - Android

Output of npx @react-native-community/cli info

info Fetching system and libraries information...
System:
  OS: macOS 15.7.4
  CPU: (12) arm64 Apple M4 Pro
  Memory: 258.47 MB / 48.00 GB
  Shell:
    version: 0.109.1
    path: /Users/burakguner/.cargo/bin/nu
Binaries:
  Node:
    version: 24.13.0
    path: /Users/burakguner/.nix-profile/bin/node
  Yarn:
    version: 1.22.22
    path: /Users/burakguner/.nix-profile/bin/yarn
  npm:
    version: 11.6.2
    path: /Users/burakguner/.nix-profile/bin/npm
  Watchman:
    version: 2026.01.19.00
    path: /Users/burakguner/.nix-profile/bin/watchman
Managers:
  CocoaPods:
    version: 1.16.2
    path: /Users/burakguner/.local/share/gem/ruby/3.3.0/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 25.2
      - iOS 26.2
      - macOS 26.2
      - tvOS 26.2
      - visionOS 26.2
      - watchOS 26.2
  Android SDK:
    API Levels:
      - "30"
      - "31"
      - "34"
      - "35"
      - "36"
    Build Tools:
      - 35.0.0
      - 36.0.0
      - 36.1.0
    System Images:
      - android-30 | ARM 64 v8a
      - android-34 | Google Play ARM 64 v8a
      - android-35 | Google APIs ARM 64 v8a
      - android-35 | Google Play ARM 64 v8a
      - android-36.1 | Google Play ARM 64 v8a
    Android NDK: Not Found
IDEs:
  Android Studio: 2025.3 AI-253.32098.37.2534.15232325
  Xcode:
    version: 26.2/17C52
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 21.0.8
    path: /Users/burakguner/.nix-profile/bin/javac
  Ruby:
    version: 3.4.8
    path: /Users/burakguner/.nix-profile/bin/ruby
npmPackages:
  "@react-native-community/cli":
    installed: 20.1.0
    wanted: 20.1.0
  react:
    installed: 19.2.3
    wanted: 19.2.3
  react-native:
    installed: 0.85.2
    wanted: 0.85.2
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: true
iOS:
  hermesEnabled: true
  newArchEnabled: true

Stacktrace or Logs

N/A

MANDATORY Reproducer

https://github.com/atlj/reproducer-max-font-size-multiplier-line-height

Screenshots and Videos

Font Scale	iOS	Android
1
2.143

Notice how lineHeight is not clamped on Android screenshots

Commencez par l’application obligatoire de reproduction et exécutez-la avec yarn android et yarn ios. Comparez les captures d’écran avec des tailles de police normales et augmentées à l’aide des commandes de configuration de l’issue ; c’est terminé lorsque lineHeight sur Android est limité par maxFontSizeMultiplier de manière cohérente avec iOS.