I have a T5 Woot Farm with Flayed III Perk and the ritual on top on the Mob farm.
Need help

Modpack: endeavour
MC: 1.16.5

I believe it is
Altar - 10 horizontal, 15 vertical
Heart - 15 horizontal, 15 vertical

Think there is a tool in Blood Magic to visualize the area.
Ritual Tinkerer - define area mode - right click the master ritual stone - shift right click master ritual stone to toggle altar/heart display.

What are the dimensions of "nearby"? I have a woot factory within 15 blocks vertically and horizontally of both my ritual and altar, is that good?

The ritual needs to have both the farm heart block and a Blood Magic altar nearby. When the farm kills mobs, then LP is generated in the altar