Raspberry Pi 4 Power Supply (AUS Official) - USB-C 5.1V 15.3W (WHITE)
If you EVER see this symbol ⚡ on your Pi screen, it's time for a better power supply.
When/if you see this symbol your Pi will underclock and run SLOWLY!
These official power supplies are typically more than enough.
Unlike the Pi-3, Your phone charger may not be quite enough here.
This listing is for a WHITE variant of the power supply which features: