Is Spider-Man: Brand New Day connected to Avengers: Doomsday?

Probably, but only in a broad MCU continuity sense unless Marvel confirms a direct plot tie-in.

Here’s the safe way to think about it:

• If Spider-Man: Brand New Day is the title of the next Tom Holland Spider-Man film, it would still be part of the MCU and could be set up by or follow events in Avengers: Doomsday.
• That does not automatically mean the two films are officially confirmed to have a direct story connection.
• The title Brand New Day also suggests a Spider-Man comic-inspired reset/fresh-start angle, which could fit Peter Parker’s post-No Way Home situation and still be only indirectly related to the Avengers film.

So the best answer is: likely connected by shared MCU continuity, but a specific, confirmed story link has not been established. If you want the exact relationship, check the latest official Marvel announcements or trailer/interview confirmations.