Of course! Here’s what you need to know:
Large publishers prefer agented submissions because the work arrives pre-vetted. They’re not wasting their time on an amateurish screed from someone who thinks they’re a writer because they own a copy of Word and know how to stuff a manila envelope full of their poorly-written, spell-check-ignored ‘manuscript’ and fire it off (unsolicited) to the President of the publishing company.
Agents exist, in part, to spare editors from sending more paper to the local recycling facility.
If you have bona fides—actual credentials—you can approach a publisher directly. But you follow their roadmap, not yours. No serious publisher accepts unsolicited manuscripts, but most will consider a query letter and book proposal (for non-fiction), or a synopsis and sample chapters (for fiction) — IF the writer conducts themselves professionally.
That last word there is doing a lot of heavy lifting in that sentence.
First and foremost, you DO NOT send an unsolicited manuscript to anyone. All they’ll do is just throw it in the trash; no reputable company accepts unsolicited material.
Writers don’t need publishing companies. They haven’t needed publishing companies for more than a decade.