Three factors are important for charging and especially for charging your devices with Power Delivery:
The charger used
The device to be charged
The charging cable used
There are differences in the compatibility and charging performance of all 3 components. All 3 components must be compatible for Power Delivery.
The power source that provides the USB-C connection must support Power Delivery in order to be able to charge a device quickly using the standard. The output power determines the speed at which a device can be charged.
As Power Delivery only works via USB-C, you need a suitable charging cable for your device. It must have a USB-C plug on both sides and be suitable for the required amperage. An electronic component (e-marker) is required in the USB-C charging cable for currents above 3 amps.
Your device must have a USB-C port that explicitly supports USB Power Delivery. You can either find this in the operating instructions for your device or recognize it by a battery or lightning bolt symbol for Thunderbolt 3/4 directly next to the USB-C port.
The charging cable in particular often throws a spanner in the works. It would therefore be very important to know which cables you have used in order to check your request; the exact type is important (preferably with a link, e.g. Amazon).
Please note that the maximum possible power supply can vary greatly with USB-C connections. This can range from 10 watts for smartphones to 100 watts for notebooks. Not every USB-C cable can charge a notebook, simply because the power supply is too weak.
The amperage is usually indicated on the plug of the cable.
In addition, the charging speed of your smartphone may vary depending on the current battery level.