Question regarding optimizing load times

Started optimizing the loading of my site and the biggest slow down comes from render blocking resources, which are

1st Party 83.7 KiB 1,350 ms
…css/bootstrap.min.css - 25.8 KiB - 300 ms
…dmxAnimateCSS/animate.min.css - 4.9 KiB - 150 ms
/dmxAppConnect/dmxAppConnect.js - 28.8 KiB - 450 ms
…js/bootstrap.bundle.min.js - 24.1 KiB - 450 ms

FontAwesome CDN Cdn 13.5 KiB 780 ms
…css/all.css - 13.5 KiB - 780 ms

can I use async/defer on these or would that break something? Or is there any other way to improve the speed on this?

Also, it shows

Reduce unused CSS
…css/bootstrap.min.css
…css/all.css(use.fontawesome.com)

does that mean they are unneeded? I am using fontawesome icons and bootstrap so I’m not sure how they would be unneeded?