The universal advice is, yes, practice, and the best kind of practice is just continually drawing/painting/whatever, trying to do it every day as much as possible, whether that means pushing your boundaries or resting in your comfort zone. Drawing every day, even if you don't finish something every day, is hugely important. Drawing stuff you're not familiar with, studies or forays into the unknown are also important, hugely important - but I feel like what you're talking about has less to do with technical skill and more with trying to chase your idols, something I also struggled with deeply and still do. It's very easy to feel like i'm just a composite of those same artists - I certainly don't feel like i've pulled it off - I don't think anyone does.

Keeping in mind that it's almost impossible to understand your own work the way anyone else does - I want to tell you that I was also someone who only started drawing seriously at 19/20 back when I left school in 2013. I had spent years fucking around kind of coasting on a rep I had for being "The kid good at drawing" without really having anything but one or two things I could actually draw. When I decided I wanted to follow this as a career I spent my "gap year" doing nothing but relearning how to draw in pen, completely different from everything I had previously done. Everything has followed from that moment, and here I am about a decade later - it is NEVER too late, and you can move much faster than I did too if you commit to really learning - I still fuck around a lot lol.

My best recommendation for how to feel like you can design the way that figures like Nira/Amemiya/Shinohara etc. can is to understand that you cannot only draw from their work - you cannot only draw from a diet of other artists in your own field. They're an important part of your study, but they and all the "Greats" consume everything - watch experimental operas, read books about lobsters or obscure textile weaving, go to exhibits on german medieval typography, take a walk through a part of a city you've never been to before and take photos. You cannot possibly know where inspiration will come from, and the more you take in from "outside our ecosystem" the more sustenance you give yourself. I've had sudden ideas for exactly how a particular design should look leap out at me looking at footage of remote Siberian town supermarkets and listening to recordings from early phonographs and watching total trash horror films and everywhere in between. The more you only consume the greats, the more you will only be capable of imitating them, replicating not just the strengths you see (Which are less unique in anyone else's hands) but also the flaws and weaknesses they have we can't understand. They're a catalyst you use to start a reaction that needs material from elsewhere to keep burning.

Above all, never lose hope and enjoy the process. You will outpace all of us if you have your heart in it.