This is a theme component that will allow you to easily change the :heart: icon with the :+1: icon (or any other font awesome 5.5 glyph you prefer).
Please, remember also that:
[quote=”pmusaraj, post:1, topic:101643”]

  • since the Font Awesome icon set has grown to 1300+ icons in version 5, we have built an internal API that delivers to clients a subset of all FA icons, that is, only those icons used by that Discourse instance
    [/quote]
    and that
    [quote=”pmusaraj, post:1, topic:101643”]
  • site administrators can also use a new site setting called svg icon subset to register their chosen icons and add them to their site’s subset
    [/quote]

Repository link:
https://github.com/discourse/new-like-icon

Before:

like%20before: 264x81,60%

like%20before2: 285x70,60%

After:

like: 267x73,60%

like%20after: 340x76,60%

Remember that you can change also:

  • color through /admin/customize/colors/
  • text through /admin/customize/site_texts/

Install it as a theme component and add the component to your main theme(s).