this Webasto 5KW water heater kit with plate heat exchanger can produce continuous tap temperature water, yes. Flow rate at tap ( once mixed with cool water via the domestic storage tank is approx 5 ltrs per minute. Warm up time from cold is dependent on coolant circuit size overall  though Webasto literature states approx 5 mins. Exact flow rates and hot water tap temperatures are also dependent on mixer valve settings. The plate heat exchanger heater coolant side will be approx 80-85 celsius, this will be reduced on the DHW circuit via the mixer valve to a chosen safe temp. For further related info please review our web links below on typical water circuits and operation modes

https://www.butlertechnik.com/technical-library/thermo-top-c300

https://www.butlertechnik.com/downloads/cms/7658/webasto-thermo-top-c-300-water-heater-installation-manual.pdf