Yes, if you have a small team of say 10 people, a very competent lead engineer can make all the difference by setting up proper testing, SCM, CI, etc. i.e., by choosing the right tools and people for the job.
However, as soon as you have a slightly larger team, these decisions will usually not be made by one single person. If you have a large project with dozens or hundreds of engineers, you'll have dedicated teams for some of these tasks, making their own desicions.
In my opinion, the most important thing then is to spot anything that will make things go haywire, communicate them and convince the right people that this has to be fixed. If you force a new porgramming language onto the whole team because it makes you, the 10x engineer, more productive, you might face endless discussions, additional training costs and a big backlash ("why do we need this now?") from the team.