It seems that Southgate decided to stick to his plan to score first and then play cautiously, defensively, but now I think his plan started to fail, because for the first time Serbia started to have some moments that can be called at least a little dangerous. Of course, I want England to play attacking soccer, but for Southgate the result is probably more important than a beautiful game.
Nevertheless, Serbia still have chances, because one goal can always be scored, but if England score the second goal, they will probably win the match with 99% probability.
This strategy will not be effective and could even result in England being knocked out of this tournament early, Southgate should still order his players to appear aggressive in the second half. Bellingham is England new hope, and he is the hero of today's victory. Statistically, England does not look too dominant, both in terms of possession of the ball and also in terms of the number of shots on target.
On the other hand, I'm pretty sure England can qualify as group winners easily, but their next journey will not be easy. Of course they have good squad depth in almost every line, but Southgate must find a strategy to win the match easily. Next England will face Denmark, they have to do it in a better way.