The defence England have at the moment is better than Argentina's backline in 2022.
The back four that started the final played for, at the time, Atletico Madrid (Molina), Spurs (Romero), Benfica (Otamendi), and Lyon (Tagliafico). The guy who scored the winning penalty was at Sevilla.
James, Stones, Guehi, O'Reilly; Livramento, Konsa, Maguire, Spence; etc. There are more names to pick from. But any combination at the back for England can be solid enough across eight games with the right methods.
I have expressed similar doubts about Kane in the past but he's at a winning club now and has the experience of those big occasions that he never had with Spurs. He's likely learned more in the last 18 months than the previous decade.
Spain are the team to beat but England have the depth and quality, and finally the right manager, to reach the very late stages of the tournament. I think they can be confident against pretty much anybody at the moment.