You can do it on browser too by using an adblocker and adding custom filters.

For hiding threads: feddit.uk##div.post-listing:has(span:has-text("/trump/i"))

For hiding comments: feddit.uk##article.comment-node:has(div.comment-content:has(p:has-text(/trump/i)))

Naturally you also need to change the instance name to that of your’s.