I don't think it's possible in Lemmy, unless you use an app (might not be FOSS though?) that adds that functionality. I'm not sure which ones though - maybe check out Sync or Connect?

PieFed can do it innately, in multiple ways. First, in the new user wizard (or in your account anytime later) you can specify that you want to see posts mentioning "Trump" or "Musk" either never, a little, or have no filtering.

Second, in addition to the standard Subscribed and All feeds, PieFed offers categories of communities, like Reddit's multi-reddit feature, so e.g. Arts & Crafts has no politics within it, though ofc News & Politics has nothing but:-D. The beauty of that is that with those, you could e.g. decide to not subscribe to any News or Politics communities, so that your Subscribed feed is empty of it, and yet still read the news as often as you like at the touch of a button. Those Feeds just became user customizable and shareable too.

The only other way to do that on Lemmy is to make a new account for every type of collection that you want, and then subscribe to the communities that you want each one to have. Which would get super annoying, super quickly:-).