Dracula by Bram Stoker is a late-19th century novel about the eponymous vampire, Count Dracula, and the humans who encounter him. It is recounted as if it were a collection of primary sources, including letters, logs, and newspaper articles. As the novel creates tension with its contrasts between science and magic and between the past and the present, there are a few ways you can approach this question.
According to the Encyclopedia Britannica, modernism is “fueled in various literatures by industrialization and urbanization and by the search for an authentic response to a much-changed world.” To explore this in Dracula, you could start by comparing the modern world of Harker to the more ancient world that Dracula inhabits. Harker even compares his journey to Transylvania to a trip backwards in time. If Britain is the future and the center of civilization, then Transylvania is the past and the wild, uncivilized frontier. The human characters utilize the latest technological advancements of their time, including typewriters, telegrams, trains, and cameras, which are all a far cry from Dracula and the older world of Transylvanian society.
The scientific method, as defined by the Encyclopedia Britannica, is “the process of observing, asking questions, and seeking answers through tests and experiments.” It seeks to collect observable facts and create theories that can explain them. The very structure of the novel lends itself well to the scientific method. By following the narrative through a series of letters and articles, the reader is forced to participate in the scientific process by treating the events of the story as information to record, process, and assemble in a meaningful way. Science and magic are often side by side, however. Dracula himself is a supernatural creature that science is unable to explain. He performs feats outside of what is scientifically possible, baffling the human characters who often rely on their confidence in what the modern world has taught them about reality.
I would recommend looking for these points of tension between the old and the new, the magical and the scientific, and relating these examples to the ways that Stoker uses modernism to respond to a world that was rapidly changing.