I disagree with your friend and I believe she's wrong about "nobody uses a camera anymore". However, it is true that many people these days (perhaps the majority) just use their phones for travel photos, as they're light, usually always accessible and the quality is good enough for most people.
I think it's important to determine what type of photos you want to remember your travels with, the best equipment to get the photos, and how much time & effort you're willing to put into learning to use the equipment. The sensors used in cameras are considerably larger than those used in phones, so they can capture more detail. Most phones these days use some type of "computational processing" for photos, where the software determines how to process the photo to get the best result. In many cases the results are reasonably good, and there are apps that allow the images to be "fine tuned".
I've also been a "serious amateur" photographer since about the mid '60s, and I typically travel with both a dSLR and a P&S, as well as my iPhone. I've found that the dSLR gives me a wider choice of settings in terms of aperture, shutter speed, depth-of-field, choice of lens or whatever, and allows me to get the results I want very quickly. I use the larger camera for most photos and use the P&S to get snapshots of things like restaurant menus, museum guides, or whatever. It's also a 'backup" in case I have problems with the dSLR (which has happened).
I'd suggest that you check out local camera stores that have very knowledgeable sales staff, and have a look at different types of cameras that may fit your needs. A travel P&S with long zoom would be a good fit for many situations, so it's not necessary to haul around a large dSLR camera. You could look at models from Canon, Nikon, Sony, Panasonic or others. Try them out in the store to determine which one you're most comfortable with (FWIW, I use mostly Canon gear). Don't forget to buy extra memory cards, lens cleaner, a spare battery, etc. If you normally use a small cross-body bag or whatever when out sightseeing, you could store the accessories in that.
One important point (and something that Rick has mentioned recently), is that mobile phones have increasingly been a target of thieves lately. If you're in a crowded location and not paying attention when you have the phone in your hand, you could lose it very quickly. I tend to leave the cameras in the hotel room when I'm out dining or touring in the evening, and use the phone for occasional pictures when I don't have access to the larger cameras. DO NOT ever leave your phone or other valuables sitting on the table in a restaurant, even if you're sitting right there.
There's lots of information online about "travel cameras", and this is one example from a store that specializes in cameras - https://blog.henrys.com/your-ultimate-guide-to-compact-cameras-for-travel/ .
One final point..... whatever approach you decide on, be sure you learn how to use the camera before you leave on your trip.