Yes. If you need to upgrade, you can transition your account to a different plan. For example, you can upgrade from an Office 365 Business plan to an Office 365 Enterprise plan.
In most cases, you can use the Switch plans wizard in your Admin center to upgrade your plan. If your subscription has more than 300 users or if you used a prepaid card to purchase your plan, the Switch plans wizard is not available. Plans that are not eligible for the Switch plans wizard can be upgraded manually. Learn more about upgrading Office 365 plans.
NOTE: When you upgrade your account, your domain name is transferred to your new account, whether you brought your own domain name to the Office 365 account or you set up a domain name with Office 365.