If you bypass heater core will engine stop overheating?
no , the heater core provides heat to the interior for the passengers
If your heater core is LEAKING engine coolant so that your engine coolant level drops too low or the engine coolant is lost completely and causes your engine to overheat then your engine can be damaged beside the mess the leaking coolant makes inside your vehicle ( you might be able to just temporarily bypass the heater core so that no engine coolant is flowing through the heater core )
In most vehicles you can see two hoses that disappear into the firewall. These carry the hot water to and from the heater core. find where they come out and return to the cooling system and connect the outgoing and incoming with one single hose. You will need to have less water in the system once you do this. If you are doing this in the winter, obviously your heater will not work anymore. Also…