Yes, there are various ways to do that. Two of them are listed
in the FAQ, via CSS in your
extra.less
template or via an option for full-width embeds. Here's a couple of examples of possible CSS, which you can tweak to your convenience:
Code:
[data-s9e-mediaembed="youtube"] { width: 1280px !important; }
[data-s9e-mediaembed]:not([style]) { width: 1280px !important; }
The first one changes only YouTube embeds, the other changes all embeds that use the default dimensions, 640 × 360. If you're trying to achieve something else but you're unsure about the CSS, you can ask here.
Thirdly, you can also theoretically edit the template of each embed but that's generally not needed, and generally not a good idea.