It is very natural that some people really hope that England can perform at the top because they have a pretty good squad. However, in the first match, England was only able to win 1-0 over Serbia. As a result of the results of this match, some people are also doubting their chances of winning the championship, but in my opinion the verdict is too quick and I am still very confident that Southgate will immediately evaluate his squad. However, overall the England national team's performance was quite good, statistically they were also superior to their opponents.
It should be like that, in the first match we can't decide anything on the performance of all the teams or the results obtained and apart from the assessment of the England team and many people who doubt them to win the Euros I think the most important thing is that they can win in their first match even though 1 goal and that is quite important for the English National team.
Personally, I think England's overall performance in their first match was not that impressive, there are still many aspects that need to be changed, especially the front line which was unable to take advantage of creating dangerous opportunities.