Oscar L. Tang and Agnes Hsu‐Tang have kept a relatively low profile as philanthropists over the years, but their names may become more familiar to the public as they are splashed across some of New York’s most prominent cultural institutions.  Tang is a retired financier who has held positions on the boards of the Metropolitan Museum of Art and New York Philharmonic. His wife, Hsu-Tang, is an archaeologist, art historian and board chair of the New York Historical. Together, they have made a flurry of record-breaking and legacy-making major gifts in recent years. The couple’s $125 million donation to the Metropolitan Museum of Art—the largest capital gift ever made to the museum— revived the Met’s plans for a new wing , set to open in 2030 as the Tang Wing for Modern and Contemporary Art. A $20 million gift to the New York Historical also earned them naming rights for its new wing on American democracy.…