Southgate played a completely unchanged team for France.
He didn’t do anything to combat Mbappe except play Englands best RB despite him being only just fit.
He didn’t go to 5 at the back, he didn’t make changes or drop attackers, he didn’t sacrifice possession, he just played the team that won the last 16 easily.
You’ve mistaken the press building up the Mbappe Walker duel with Southgate obsessing over it.
Your criticisms of Southgate are so detached from what actually happened it’s impossible to take them seriously - you’ve just recycled criticism from the Euro final where he actually did make the mistake of worrying too much about the opposition and made defensive changes.
He’s an average manager and there’s plenty to legitimately criticise but you’re so desperate to portray him as the worst thing that ever happened to football you’ve lost the plot.