The first thing to do is a google search like this “fritzing part Heltec ESP32 WiFi V3 Oled” which will find parts that are not in core parts. In this case that doesn’t appear to include this board although there are number of others available. Unfortunately making parts is a complex task. These two tutorials apply to the current versions of Fritzing
and may help if you want to do it yourself. If you need a small number of boards done (such as only this one) it is usually easier to get someone like me who is familiar with making and modifying parts to do it for you. It isn’t all that difficult for me, but is likely a lot less so for you.