Bringing a dish to a party typically implies that you are contributing to the event and sharing your culinary creation with others. In most cases, it is considered polite to leave the leftovers for the host or other guests to enjoy after the party. Taking home the leftovers without explicit permission may be seen as rude or inconsiderate.
However, there can be exceptions depending on the circumstances and the relationship you have with the host. If there is an abundance of leftovers and the host offers them to the guests, or if the host insists that you take some home, then it would be acceptable to do so. Additionally, if you brought a large dish or made a significant contribution to the meal, it might be appropriate to discuss with the host beforehand if you would like to take home the leftovers.
In general, it's always a good idea to be considerate of the host's efforts and the overall dynamics of the party when deciding whether to take home leftovers. Being mindful of the occasion and expressing gratitude for the invitation and hospitality is a great way to ensure a positive and respectful social experience.