How can we guide you if you don't provide even basic specs for the leds you plan to use?

Whether or not you use multiplexing is really dictated by the leds - in many cases you can't multiplex as the pulse current will smoke your leds or simply become unmanageable. For example: if your led needs 1A for the best brightness without multiplexing and you want to use 16:1 multiplexing - then you'll need to pulse the led with 16A. Apart from the high current mosfets etc you'll need to use, there is pcb trace resistance, EMI and so on to contend with.