As you are a beginner you will initially need a camera that does everything, simply because you don't yet know what your preferred subject will be. Interchangeable lens cameras come in two types (Mirrorless (MILC) & DSLR. Pentax only make DSLRs. Mirrorless cameras use a screen as a viewfinder which gives you a representation of the final image. These are not to everyone's taste. DSLRs use pentaprisms for a more natural view, like film cameras.) and four sensor sizes. Of the sensor sizes, Medium format is huge and expensive, not really a beginners camera. Micro 4/3, the smallest, is very good, the lenses and bodies are generally smaller, they are great for landscapes, macro and wildlife but you don't have as much control over depth of field. It also doesn't handle noise/grain/speckles caused by high Iso (sensitivity) as well as full frame or APSC. Full frame and APSC are the two most popular. Full frame is the equivalent of film, very high quality but a bit larger, heavier and more expensive than APSC. APSC is a smaller sensor but still very high quality, lenses are smaller as are the bodies and it is generally cheaper. In terms of Pentax, all are robust and reliable, with weather resistance and in body image stabilization (IBIS). the K1ii (Full Frame) has been described as the best landscape camera you can buy but it isn't small and the initial outlay could be high. Pentax APSC has two offerings, both give you great image quality, the KP is quirky and hugely popular amongst members here, the K70, also popular, is the cheaper and more conventional unit. Both are capable of covering all aspects of photography. They also won't break the bank. Regarding other makes (I am no expert so I will be a bit general) Canon are the big boys but they aren't necessarily best. I find the styling a bit bulbous. The entry level cameras have some great features but don't have weather sealing or stabilization. They are also a bit plasticky, but they are cheap! Better quality offerings get very expensive, very quickly. Nikon is similar but by all accounts a bit more techy. The autofocus is very good as is battery life and image quality. Sony image quality is excellent as is autofocus and video capability but some of the menu systems can be frustrating. Sony aren't cheap. Sony only make mirrorless, the full frame mirrorless (A7 series) being the stars, but you are looking at £2k. Then there is Fuji. Fuji make cool cameras. They are all mirrorless nicely constructed and quite retro looking. Image quality is excellent and they perform really well. There are some reasonably priced options like the X-T30 & X-T200. The best Fuji's for beginners are APSC. Regarding recommendations, you need to decide whether you want a traditional view finder or an electronic screen. If you have any optical issues you need to look into whether a screen will cause headaches. There are some real benefits to an electronic viewfinder but by the same token, some people just prefer the view through glass. In terms of Mirrorless, I would look at Fuji, new, maybe an X-T30, used, an X-T3. Mirrored, Pentax! People quote a lack of physical support (shops) as a reason to discount Pentax, but as everything is now done online, that point is moot. Also, Pentax Forums is unique in its supportive membership. A new KP or K70 with a lens (18-135mm) will come in cheaper than the equivalent competition and will do everything you need. Second hand, a K3ii is a pro APSC that is built like a tank and won't cost a fortune. Pentax weather RESISTANCE (shower proof but don't swim with one) and stabilization means they are great for poor light or adverse weather. APSC sensors give you the best compromise for all types of shooting and the camera buttons and dials can be customized to work with you.
Bottom line, all cameras are good and will do a job. Don't spend a fortune straight off the bat, work with a camera make for a bit so that you know it is right for you as changing systems always costs money, and, do your research. Lots of people shoot with Canon because its the only name they know, they then recommend canon to their friends and so it goes on. They are the Manchester united of the camera world. Having lots of supporters doesn't make them the best