The Lotus Sutra’s grand claim is that all the Buddha’s teachings — seemingly varied, even contradictory — are upaya (skillful means), adapted to different beings, all leading to the one great vehicle. Every being without exception will reach buddhahood.
Its twenty-fifth chapter, on the bodhisattva Avalokiteshvara (Chinese Guanyin, Japanese Kannon), is widely recited as a standalone sutra across East Asia.