But Plato doesn't lay out "the truth." He presents beautiful dialogues that allows the reader to consider, agree, disagree or digress. Try reading the Parmenides. Here, the impossibility of unity is presented alongside the impossibility of difference. It shows the limits of language and maybe thought— or read the symposium for radical ideas about the nature of love.
Or, hell, read Xenophon's Socratic dialogues. He was more radical than Plato, though they were both students of Socrates. Xenophon turned into a mercenary and defeated the king of Persia. Then wrote extremely practical dialogues about getting rich.
Philosophy isn't about truth. It's about the love of wisdom and, ultimately, wisdom is about living a better life. Philosophy includes material that cannot be expressed with words.
Finally, Pythagoras—who coined the word philosophy. He wrote nothing out of principle and yet his worldview is arguably the most transformatively modern. Newton, Copernicus, Kepler and Gallelio all credited Pythagoras for their findings. He seemed to believe that the world was made of math and that the natural harmonies of mathematics would manifest in the harmonies of the cosmos. This idea is still resonant in the sciences — like in the groundbreaking discovery of harmonic peaks in the cosmic microwave background radiation. Pythagoreans conducted the first empirical test of a mathematical hypothesis (that bronze chimes in ratios of 1:2 and 2:3 would sound consonant).
When you read about groundbreaking wisdom that is over 2000 years old, it gives perspective on how we might build a society that similarly endures.