For your maneuvers, the DC is 8+proficiency bonus+either str or dex modifier(higher of the two). There are two ways to increase this. For the first, proficiency, you start with +2 proficiency, and gain one at levels 5, 9, 13, and 17. Since early access only goes up to level 4, you can't add any more to it this way until more content is released. The other way is to increase your str or dex to a higher amount, and as there's no equipment that seems to effect stats(as far as I have found), currently the only way to do so is via the level 4 feat, either through using the ASI to add +2 to either str or dex, or take a feat that adds +1 to either and gives an additional gameplay related feature.
