Can I use
?

Document.execCommand()

- UNOFF

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

IE

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

Edge

  1. 12 - 85: Supported
  2. 86: Supported

Firefox

  1. 2 - 8: Not supported
  2. 9 - 80: Supported
  3. 81: Supported
  4. 82 - 83: Supported

Chrome

  1. 4 - 85: Supported
  2. 86: Supported
  3. 87 - 89: Supported

Safari

  1. 3.1 - 5.1: Support unknown
  2. 6 - 13.1: Supported
  3. 14: Supported
  4. TP: Supported

Opera

  1. 9 - 9.6: Support unknown
  2. 10 - 70: Supported
  3. 71: Supported

iOS Safari

  1. 3.2 - 4.1: Not supported
  2. 4.2 - 6.1: Support unknown
  3. 7 - 13.7: Supported
  4. 14: Supported

Opera Mini

  1. all: Not supported

Android Browser

  1. 2.1 - 4: Not supported
  2. 4.1 - 4.4.4: Supported
  3. 81: Supported

Blackberry Browser

  1. 7: Not supported
  2. 10: Supported

Opera Mobile

  1. 10 - 12.1: Supported
  2. 59: Supported

Chrome for Android

  1. 85: Supported

Firefox for Android

  1. 79: Supported

IE Mobile

  1. 10: Not supported
  2. 11: Supported

UC Browser for Android

  1. 12.12: Not supported

Samsung Internet

  1. 4 - 11.2: Supported
  2. 12.0: Supported

QQ Browser

  1. 10.4: Supported

Baidu Browser

  1. 7.12: Supported

KaiOS Browser

  1. 2.5: Supported

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

Resources:
execCommand and queryCommandSupported demo
MDN Web Docs - execCommand