Certainly, but there can be a lot of nuance to this answer, as there are many different approaches that drone (UAS) operators take to meet their desired relative/absolute precision and accuracy goals. You can use the C4Gnet.XYZ services, real-time or static, as part of such varied approaches - when appropriate.

For many drone operations, setting up a base on the site can be the best choice. Be that for real-time (RTK), or post-processing (baseline and PPK). This is because a very short baseline length can yield the best results. However, if your site is only a short distance from a C4Gnet.XYZ station (e.g., under 10km on a good iono day), this could work well for RTK and/or static post-processing. Some users use VRS for their real-time data, and/or for establishing ground control points (GCP). Some users will use Virtual Rinex, generated for virtual locations in their project area.

Generally, working without GCP is not a preferred choice, unless you are only interested in relative precision, and even for that, including at least some GCP can be a best practice.

One aspect of processing drone data is the inertial (IMU) data, that when processed together with the observations from the on-board GNSS, in a PPK workflow, has grown in popularity. It is not as if PPK is much different than RTK (it is simply delayed RTK so to speak) but the addition of the IMU, and precise orbit data, that can make a difference. Your drone vendor can recommend software to do this PPK/IMU step. This is essentially the same as many mobile mapping workflows.