Spoiler: she won't. Werhmacht Walz already expressed support for "Greater Israel," ie accelerated and expanded settler-colonialism and genocide.
Harris supports Israel because the US Empire needs it. It serves as a rabid dog for the US to terrorize the Middle East, securing the Petro-Dollar by which the US maintains monopoly over global Financial Capital, and Imperialism in the Global South.
She will not change, it isn't a moral issue but an economic one.