Artemis might use a swipe gesture to visually hint at the relation between upvoting and boosting, as shown in the main animation. Here’s a static app mockup with both swipe levels displayed. I’d also imagine that there should be a setting that auto-upvotes posts when boosting.
I think that’s how it functions for Mastodon, but Lemmy and Kbin use boost more as “+2 upvotes”, as it’s used as the scoring metric for the sorting algos.