A higher-wattage charger is useful only when the device and charging protocol can use that power. It can also be valuable when one charger must serve several devices, but the largest number on the box is not automatically the best choice.
The device sets a charging limit
Phones, tablets and laptops negotiate supported charging profiles. If a device accepts 30 watts, connecting a compatible 100-watt charger does not normally make it charge at 100 watts.
Compatibility with the relevant protocol matters as much as the headline wattage.
Laptops can have a minimum practical power level
A low-power charger may slowly charge a sleeping laptop but fail to keep up while the computer is under heavy load. Compare with the manufacturer-supplied adapter and supported USB-C profiles.
Multi-port chargers redistribute power
When several ports are active, the charger may divide its total output. Read the power-allocation table to confirm that the laptop still receives enough power when a phone is connected.
Cable ratings matter at high power
A cable can be the limiting component. Use cables rated for the required current and protocol, particularly for high-power laptop charging.
A little headroom can add flexibility
A charger moderately above your current need can support a future tablet or laptop and may run multiple devices comfortably. Excessive unused capacity simply adds cost or size.
Bottom line
Choose charger wattage from the devices and port combinations you actually use. Protocol support and cable capability are part of the same decision.