First lens to purchase for X-T4...primarily landscape

I haven't had a camera in ages, since my daughter ran off with my two Olympus M43 cameras, but I recently have had a need to print 20x30 poster backdrops and obviously my cell phone won't cut it.  These backdrops will be used for product photography and dioramas.  Which kit lens do you think would suit best?  Or should I buy a body only and a different lens?  I might also be required to do some of the product photography myself with an indoor setup (which I would have to purchase) and that would be a different situation.  I haven't done this work for many decades, and at that time I had a film camera with a 50mm and 135mm.  Here are rough examples of the type of backdrop I need to photograph, taken with my cell phone.  Obviously I would need to take more care with the photo I was actually going to use.  I get a bit confused with equating the lens designations between FF and APS-C.  Not sure what the multiplication factor would be.  I would possibly purchase more lenses later, but one is all that I can afford at the moment, or at least until I see if I can make this work.  I have looked at some full frame cameras as well, but I think they would be overkill.  I like the dials on the top of the X-T4, less menu to fiddle with in a hurry, I like the IBIS as my left hand is shaky now and then, and overall I like the handling of the camera.  I never got used to the dslr bump, and the Olympus cameras were a bit too small and I hated the menus.  NOTE:  These photos are from my Google 4a cell phone.