In the mission "Numa Numa Trail" you are rescued by the 93rd Infantry Division. One of the troops in the 93rd is named Lewis Howard. Lewis's brother, Major Howard, is in Call of Duty: WW2. Lewis says a line of dialogue confirming this.
Canonically in the same timeline as Call of Duty: WW2 (2017), thanks to the presence of Lewis Howard, brother of Marcus Howard from WW2.
Oscar-Winning Cinematographer Hoyte Van Hoytema, known for his work on Oppenheimer (2023) and Interstellar (2014), is the Director of Photography for Call of Duty: Vanguard.