Fast charging depends on three things working together: the charger (adapter), the cable, and your phone's supported speed. A phone that supports 20W won't charge faster on a 65W brick — but a slow 5W charger will bottleneck a fast phone. The sweet spot for most modern phones is a 20-30W USB-C Power Delivery (PD) charger.
Cables matter too: use a USB-C cable rated for the wattage you need (some cheap cables cap at low speeds or lack data lines). For newer phones and laptops, a good 240W-rated USB-C cable future-proofs your setup. Match the three parts and you'll get the full, safe fast-charging speed your device is capable of.