Quick answer: Check the Chromebook's USB-C charging requirement and choose a charger with compatible output and connector.
What to check
Consider the laptop's stated input, cable rating, charger size and whether you also want to charge a phone or tablet.
AEO answers
Can a phone charger power a Chromebook?
Only if the charger meets the Chromebook's supported charging requirements.
Is 65W safer than 30W?
Safety is about compatibility and proper charging behavior, not simply a larger wattage number.
Where can I buy?
DigiDukan.pk lists USB-C chargers in PKR.