In the absence of details as to what you are doing now, we can only assume what your current shooting technique is. There are many possible shooting technique related causes of the issue you describe.
There can also be issues of unrealistic expectations, even when using the best gear available. All gear has limits, no matter what the marketing departments may say about their latest, greatest, most expensive new lens or camera.
This answer to Zoom or Prime Lens(es) for Wildlife Photography on Limited Budget (Nikon D500) says:
The truth is there are a lot of things many photographers would like
to do that no camera/lens has the capability of doing. The thing that
separates the great 'Photographers' from the complainers who always
blame the limitations of their gear for their work that doesn't meet
their lofty expectations based on the marketing hype machine of the
camera makers is that the 'Photographers' learn to push the limits of
the gear at their disposal while also finding ways to work just within
those same limits.
What would be the best thing to do in this situation? (As in upgrading and upgrading to what?)
Upgrade neither until you are sure you don't need to upgrade your photographic technique first.
Please don't misunderstand this as flippant or taking a cheap shot at a budding photographer. It isn't. It is an encouragement to decide to put in the learning and practice to develop the technique and compositional skills that better images truly require, rather than chasing better image quality through endless GAS (Gear Acquisition Syndrome).
It's covered in much greater detail in this answer to How to improve image sharpness on Canon 700D? and it would be a bit redundant to repeat that entire answer here, though most of it would probably apply to your current situation. We'll hit a few of the highlights:
How sharp your images turn out usually has a lot more to do with proper technique than with the gear you use. On the hardware side of things, the lenses you are using will affect sharpness a lot more than the body/sensor you are using. If you are using only lower end consumer grade zoom lenses, no camera body will make any difference until you upgrade the lenses and practice proper technique first.
Most new photographers benefit far more from improving their knowledge and skill than they do from an incremental or even quantum upgrade in the gear they use.
This answer to When should I upgrade my camera body? applies equally to lenses, lights and modifiers, etc. as it does to camera bodies. Until you can identify what is causing your images to fall short of what you wish them to be, you're not ready to identify what solution will be most likely to allow you to reach your goal.
As the accepted answer to Is replacing all my Fujifilm gear with this Canon zoom lens an upgrade? says:
While it is true that better gear won't make you a better photographer, it is equally true that any photographer is limited by the capabilities of the gear being used.
There's an old saying that has been around photography for a very long time:
Gear doesn't matter.
It's certainly true, but it is only half the truth. The rest of the truth is this:
Gear doesn't matter - until it does.
When the technical capabilities of your gear are not up to the task for the shots you want to capture, then and only then will the gear matter.