Yes. The system will automatically make the charge adjustments for you.
For example, let's say you are on a Plus plan and are paying $49 per month. In the middle of your billing cycle, you choose to upgrade to an Enterprise plan at $149 per month. We would then charge you a prorated fee of $74.50 to cover your upgrade for the rest of your billing cycle. You will then be charged $149 when your new billing cycle begins.
If you're not sure how to change your plan, check out this help document.