You need to follow the formal procedure.
これは本式な茶会です。
This is a formal tea ceremony.
noun which may take the genitive case particle 'no', na-adjective, noun
in earnest; serious; full-blown
Used when something becomes serious, full-scale, or reaches its peak, often with a nuance of intensity or commitment.
本式の冬が到来した。
Full-blown winter has arrived.
彼は本式に勉強を始めた。
He started studying in earnest.