The phrase "is deeply knowledgeable" is correct and usable in written English.
You can use it to describe someone who has extensive knowledge or expertise in a particular subject or field.
Example: "Dr. Smith is deeply knowledgeable about ancient history, making her an invaluable resource for our research project."
Alternatives: "has profound knowledge" or "is highly informed."
He is deeply knowledgeable about the country's pop culture, its shared televised imagery, peppering his speech with references to films, books, artists.
And Clark is an indispensable guide not so much because of what he knows — though he is deeply knowledgeable — as because of his unabashed enthusiasm for the art that he shows us.
As long as such a person is deeply knowledgeable about academic subjects and knows how to live well, that person would have all they need for wisdom.
Their tastes are "extravagant" and they are "proud to spend," he said; but beneath the surface ostentation his Middle Eastern clients are deeply knowledgeable about mechanical watches.
"It helps to be deeply knowledgeable about an area — to know the people, to know the language, to know the history, the culture, the literature.
Judge Wilkinson told Charlie Savage of The Times, "I think he's balanced, he's moderate, and he's deeply knowledgeable about law".
"It helps to be deeply knowledgeable about an area to know the people, to know the language, to know the history, the culture, the literature.
Our writers from across the globe will offer a regular diet of personal dispatches from regions they are deeply knowledgeable about, and on issues they, and our readers, feel strongly about.
A review of Mr. Biden's debate performances shows him to be deeply knowledgeable across a range of topics, reflecting his nearly four decades in Washington, where he is chairman of the Senate Foreign Relations Committee.
My fellow judges, both of whom are deeply knowledgeable and passionate about literature, argued their positions eloquently, and I'm sincere when I congratulate Edna O'Brien on the award.
A quarter-million strong, by their estimates, they are deeply knowledgeable, a little prickly about being dismissed as nerds, and so enthusiastic that Mr. Buffett's following of devoted investors will seem disengaged by comparison.
