Mega 5v VCC supply/output concerns

First project utilizing MPs/Arduino--4 DC motors and 6 relays to control open/closed valves.

Hardware:
Arduino Mega
two 4-channel relay boards (6 relays being used)
two TB6612FNG motor driver boards
DS3231 RTC

All components need a VCC but is the mega up to the challenge of pushing 5v to both relay boards and both motor drivers (I've initially connected the RTC to the 3.3v pin) simultaneously?

IF so, it looks like I can simply define a pin # and write it as high to supply that 5v once I've utilized all the given 5v pins. Is this correct?

Thank you!

EFox:
All components need a VCC but is the mega up to the challenge of pushing 5v to both relay boards and both motor drivers (I've initially connected the RTC to the 3.3v pin) simultaneously?

Depends on the current draw. Which depends on exactly which boards, and can be measured.

IF so, it looks like I can simply define a pin # and write it as high to supply that 5v once I've utilized all the given 5v pins. Is this correct?

No, a tempting idea but logic pins cannot act as power supplies as they have way too much resistance and will be easily damaged by decoupling cap inrush currents.

Thank you!

Thank you!

I have minimal experience with electrical engineering and zero with micro controllers and this project was essentially dropped in my lap because I had some time available.

Does the VCC have to come from the Mega or can I simply match the motor driver's requirements with those of a power supply?--Already utilizing an independent power supply to send VM to the drivers.

Again, thank you.

Evan