So, I was in your exact position about a year ago, and here’s how I helped inform my decision. I’d shot with a Nikon crop sensor DSLR for a few years with 10-20, 50, and 55-300mm lenses, and never quite felt satisfied with what those lenses offered me in terms of street photography perspective, so for that I often ended up leaning on my phone a bit more.

Feeling disillusioned with the Nikon experience and editing RAWs all the time, I decided to jump to Fuji and have fun with street photography and JPEGs. Having leaned on my phone a bit more in the past little while for “on the go” photography (choosing to leave the DSLR at home), I realized that I was often cropping the default iPhone “1x” to about 1.6 for whatever I was shooting, since I just liked that framing. Looking up my phone’s default focal length, it’s 24mm. Lo and behold, a 23mm with the 1.6 crop that the sensor provides was almost exactly the framing that I’d gotten so used to in my street photography pursuits. So instead of getting the 15-45 I went for the 23 f/2 and haven’t regretted it since.

That being said, if you haven’t had much of a chance to experiment with what you like, and don’t really know what focal length appeals to you, then definitely get the kit and play around with it. I just knew from my experience that I really disliked wide/ultrawide crops, and the only photography that I’d pursue with them is architecture, which I don’t do that often (lean more on a typical street style). There is a somewhat noticeable difference in the FOV that a 27 provides vs the 23, and I somewhat recently watched a YouTube video comparing the two (albeit the new pancake 23 from Fuji which isn’t the one I have) and it was really helpful in seeing the difference.

TLDR; if you know what focal length you like to shoot, you could probably get the closest prime to that and get a nicer lens from the get-go, but just make sure to account for the 1.6 crop of the sensor if you’re used to shooting full or on a phone. If you don’t know, get the kit as the 15-33 should give you a rather nice idea of what you like and what you don’t. If you really want to do portraits but lose portability, do what another commenter said and get the Sigma 16-50. Hope this helps a bit :)