I live near Mexico and to my understanding La Dia De Los Muertos is a mixing of both Catholic and pre-Columbian practice.
In Mexico it’self they have elaborate altars, with bread of the dead often shaped as skulls and skeletons, on the altars they often have liqour and cigarettes and food, thing the deceased used in their earthly life. And candles as well.
A lot of people will spend the night at their dead forebearers graves. Again the cemetary will have gifts liqour, tobacco and food. The graves are decorated heavily with marigolds.
It is a party day, a celebration of life, and people beleive the deceased come back for the night figuratively and actually consume the gifts.