On iOS, Arctic has it.

Connect on Android has it

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.

Mlem for iOS let‘s you filter for keywords

Voyager

Copy past from our “newbie welcome package” which is itself pasted from: https://jlai.lu/comment/12441672

With keyword filter:

• Voyager
• Connect
• Eternity
• Interstellar
• Raccoon
• Summit
• Sync
• Tesseract
• Thunder
• Boost

Without keyword filter:

• Alexandrite
• Jerboa
• Lemmy UI
• mlmym
• Next
• Photon
• Quiblr