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 - 112: Supported
  2. 113: Supported
  3. 114 - 116: Supported

Edge

  1. 12 - 112: Supported
  2. 113: Supported

Safari

  1. 3.1 - 5.1: Support unknown
  2. 6 - 16.4: Supported
  3. 16.5: Supported
  4. 16.6 - TP: Supported

Firefox

  1. 2 - 8: Not supported
  2. 9 - 112: Supported
  3. 113: Supported
  4. 114 - 115: Supported

Opera

  1. 9 - 9.6: Support unknown
  2. 10 - 98: Supported
  3. 99: Supported

IE

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

Chrome for Android

  1. 113: Supported

Safari on iOS

  1. 3.2 - 4.1: Not supported
  2. 4.2 - 6.1: Support unknown
  3. 7 - 16.4: Supported
  4. 16.5: Supported

Samsung Internet

  1. 4 - 20: Supported
  2. 21: Supported

Opera Mini

  1. all: Not supported

Opera Mobile

  1. 10 - 12.1: Supported
  2. 73: Supported

UC Browser for Android

  1. 13.4: Supported

Android Browser

  1. 2.1 - 4: Not supported
  2. 4.1 - 4.4.4: Supported
  3. 113: Supported

Firefox for Android

  1. 113: Supported

QQ Browser

  1. 13.1: Supported

Baidu Browser

  1. 13.18: 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