Yes, that’s right. Wattage is a measurement of how much power a supply can provide. If your computer requires 45w, but your power supply can provide 65w, you will be fine.
As long as it is the same voltage and connector type you can use a higher watt adapter. It will charge the battery a bit faster but other than and the size of the brick you will see no difference. The laptop will only draw the current it needs while running.