Where can I find a generic weight take off chart for planes? I looked online but maybe I'm not looking in the right place? Related: How do I use the takeoff and landing distance charts in the C172 POH?
Such a thing does not exist. There is nothing like a "generic" aircraft, the sheer number of variables and breadth of their values makes any attempt to produce such a thing highly implausible.
Useful takeoff performance data is only available for fully engineered and prototyped aircraft. The prototype can be computationally simulated but that is not some web app, it is a team of researchers with access to specialized facilities. (Something like a flight simulator is not an engineering tool. Flight simulators just copy existing aircraft data, they do not do any fluid dynamics or similar computation.)