What are ways to treat bulging veins naturally?

None that works. Varicose veins are due to leaking valves in the saphenous vein system. There is a strong hereditary component. There are many potential home remedies such as horse chestnut, witch hazel and certain kinds of berries but none of these work. If you have varicose veins, then you should see a vein specialist for a f/u venous evaluation including a venous ultrasound.
Compresion. Compression stockings are the most effective way to help bulging veins. Well fitting graduated compression not only helps the symptoms but also temporarily improves circulation.