What lens/lenses for traveling cities with a cropped sensor?

Hello there!Before I’ll start writing my question I want to tell what gear I’m using and what type of photography I want to approach. I’m using the M50 Mirrorless camera from Canon with the kit lens 15-45mm f4.5-6.3. I also have an adapter to EF lenses and I bought the EF 50mm 1.8 STM. I like shooting landscapes, buildings, street photography and portraits but I quickly find some disadvantages of my system:1. Having a ASP-C sensor gives me the 1.6x crop factor. Making my kit lens and my 50mm more zoomed in for my needs. I use my 50mm (80mm in cropped world) mostly for portraits and I can’t find other uses for it sadly. Buildings looks zoomed and without perspective for instance. 2. Having this wider kit lens is great for everything else than close-up portraits but I find that is making my pictures, sometimes, looks  like on amateur point and shoot cameras. The corners are also being distorted and I’m having trouble in making beautiful compositions with this lens. I’m mean it’s not bad at all, but still...I also have the iPhone XS Max and it’s impressing how the shoots looks sometimes better than on my kit lens in terms of composition, colors and white balance. Now I’m having a trip in London and I want to pack small for this trip. I want to find a perfect solution of shooting street photography, architecture & buildings. Ok! Maybe some portraits too.. I thought about this:1. having multiple lenses it’s hard for me to change lenses fast and on the location with the risk of losing a beautiful scene. 2. having a compact setup would make an easier task to switch from a wide lens to more telephoto one.So my questions are:1. What lenses should I take in? And should I take in consideration the wider lens from my iPhone? 2. If I have the 50mm (80mm cropped) how could I use it in my advantage beside some portraits?3. How could I use the kit lens and avoid distorted corners, inclined buildings in cornersHope you could help me find some answers.