If you like following someone but they boost too much stuff, you can mute just their boosts without hiding their ordinary posts:

1. Log into Mastodon
2. Go to profile of the person whose boosts you want to hide
3. Click on ︙or ⋯ at the top and select "Hide boosts from…" (or "Hide reblogs" on some apps)

If you change your mind, go back to their profile and select "Show boosts from…" (or "Show reblogs").

There's lots more info about muting and blocking on Mastodon at https://fedi.tips/blocking-and-muting-on-the-fediverse