Can I use
?

Document.execCommand()

- UNOFF

Allows running commands to manipulate the contents of an editable region in a document switched to designMode

Chrome

  1. ✅ 4 - 134: Supported
  2. ✅ 135: Supported
  3. ✅ 136 - 138: Supported

Edge

  1. ✅ 12 - 134: Supported
  2. ✅ 135: Supported

Safari

  1. ﹖ 3.1 - 5.1: Support unknown
  2. ✅ 6 - 18.3: Supported
  3. ✅ 18.4: Supported
  4. ✅ 18.5 - TP: Supported

Firefox

  1. ❌ 2 - 8: Not supported
  2. ✅ 9 - 136: Supported
  3. ✅ 137: Supported
  4. ✅ 138 - 140: Supported

Opera

  1. ﹖ 9 - 9.6: Support unknown
  2. ✅ 10 - 116: Supported
  3. ✅ 117: Supported

IE

  1. ✅ 5.5 - 10: Supported
  2. ✅ 11: Supported

Chrome for Android

  1. ✅ 135: Supported

Safari on iOS

  1. ❌ 3.2 - 4.1: Not supported
  2. ﹖ 4.2 - 6.1: Support unknown
  3. ✅ 7 - 18.3: Supported
  4. ✅ 18.4: Supported
  5. ✅ 18.5: Supported

Samsung Internet

  1. ✅ 4 - 26: Supported
  2. ✅ 27: Supported

Opera Mini

  1. ❌ all: Not supported

Opera Mobile

  1. ✅ 10 - 12.1: Supported
  2. ✅ 80: Supported

UC Browser for Android

  1. ✅ 15.5: Supported

Android Browser

  1. ❌ 2.1 - 4: Not supported
  2. ✅ 4.1 - 4.4.4: Supported
  3. ✅ 135: Supported

Firefox for Android

  1. ✅ 137: Supported

QQ Browser

  1. ✅ 14.9: Supported

Baidu Browser

  1. ✅ 13.52: Supported

KaiOS Browser

  1. ✅ 2.5: Supported
  2. ✅ 3: Supported

To determine what commands are supported, see Document.queryCommandSupported()

Resources:
execCommand and queryCommandSupported demo
MDN Web Docs - execCommand