In short - usually , Yes.
We will analyse your website to make sure it contains the words that your target audience will be searching for. If these words are not there in the correct place, then Google may decide your site is less relevant than a competitiors site.
All changes we recommend are first put to you before the changes are made.
If you prefer us to manage the whole project, you can simply provide us with your hosting details and we will manage the project from start to finish.