Gear matters, of course. That's a trivial remark. Some things are simply impossible without proper gear, or are possible only with insufficient results. You can crop a 50mm shot to mimic a telephoto lens, but only to a certain limit. Or you can stitch 50mm shots to mimic a wide lens. But that won't work in every scene, not with moving objects. Good natural light is the optimal choice, but not always available, or not always optimal. Then you might need a flash or reflectors. And so on. And thus gear matters, of course.
On the other hand, gear matters much less than a good eye and good technique. Skimming through your old images, you may find not too much differences between keepers taken with different cameras. The simple reason for this is that you are looking at images you kept. With better gear, you might have been able to get them more reliably, or in even better quality. The eye will still matter. But to have a camera that does not let you down simply helps.
I had a second camera with an MFT sensor, the Panasonic GX85. For relatively cheap money, you can get this camera plus the nice 42,5mm portrait lens at F1.7. A full frame equivalent is available, albeit at double the weight and price. If you take a 85mm and set F3.5 and increase the ISO accordingly, you will get the same image, in terms of DOF, Bokeh and noise. But you can take a 85mm F1.8 and use it wide open on full frame, getting better Bokeh and less noise. That is is simply an option which is not available on MFT.
Another example for options which are only possible with more expensive gear is wildlife. Usually, the animals are far away because they are shy, and the morning or evening light is the most interesting one, but weak. Birds in flight offer further challenges for the auto focus system. If you want to go into that area of photography, be prepared to spend some money on a telephoto lens and a camera that can focus fast and accurately. For this kind or photography, reliability is everything. However, the biggest hurdle for me is the patience and time that you have to spend for this kind of photography. Anyway, sometimes you get a lucky shot.
If we talk about light, there are two topics: artificial light and low natural light. Both offer new problems in terms of gear. Concerning flashes, one should at least consider a mighty on hot-shoe flash with a head that can be turned and bent for bounced light from walls or ceilings. Light formers and reflectors are the next step. Necessary? It depends. In fact, a simple window light can often be the better choice.
Low light photography obviously rises the problems that come with high ISO. Again, modern cameras are simply better. If that matters or not, depends on the style you are up to. I learned to value the full frame advantage in noise handling. The so-called full frame sensor is in theory about one stop ahead of an APS-C sensor. This does not sound much. But I found that it is exactly the boost I needed. I would not hesitate to use the Nikon Z5 up to ISO1600. On my Nikon D7500, this was just one stop too much in terms of noise and lost dynamic range.
There is another advantage of a better camera: There are usually better lenses available. How much better ? Looking through my old images, I have often difficulties to spot the difference between lenses in old images on my disk. The simple explanation is that I kept only the successful images, of course. But it is more easy to be successful with good lenses. Pixel peeping or careful inspection may reveal even more advantages of the heavier, larger, and more expensive optical equipment.
That all sounds as if I'd unconditionally recommend buying new gear. I don't. As I tried to convince you and myself, better gear just opens more options. It is no guarantee for better images. Amateurs like myself should keep that in mind. For a proof, here is an old image taken with a simple D70. My new camera may yield such images more reliably, and I can zoom in more due to the higher solution and the better lenses. But the price to pay and the improvements in the results should always stay in balance.