The American painter Cy Twombly returned to large-scale paintings in the last two decades of his life, the period Gagosian highlights in this exhibition. The shift came after Twombly’s 1994 retrospective at the Museum of Modern Art and the 2001 critical success of his series “Lepanto.” Twombly not only enlarged his scale, he opted for brighter colors, using loops and slender lines to evoke flowers in motion. Come see, up close, the great painter’s late creations. —Clara Molot