okay so I finally bit the bullet and got the a7IV because my friend said it was the best for my trip to Italy next month but now I realize it didnt come with a lens and im honestly just so lost looking at all the options. i spent way more than i should have on just the camera part and my bank account is screaming at me but i need something to actually take photos with right?? my cousin told me to look at Tamron because they are cheaper than the Sony ones but there are like a million of them and I have no idea what the numbers even mean.

im getting really frustrated because every time i google something i get more confused like what is a 28-75 vs a 28-200 and why does one cost way more if the numbers are smaller?? i just want to take nice pictures of the buildings in Rome and maybe some food shots without having to carry a giant suitcase of gear around all day. im really worried im gonna buy the wrong thing and waste my money and then have blurry photos of the coliseum. it feels like i need a degree just to buy a piece of glass.

here is what im dealing with:

• i can only spend like 800 maybe 900 dollars max because i still have to pay for hotels and stuff
• we leave in three weeks so i need to order it like yesterday so i can practice
• i want one lens that does everything because i dont know how to change them fast and i dont want to get dust inside the camera
• it needs to be light enough to carry for 10 miles a day because we are walking everywhere

sorry if this is a stupid question but i literally dont know where to start and the more youtube videos i watch the more i feel like i should have just stayed with my iphone lol. does anyone have a suggestion for which tamron one is the easiest for a total beginner who just wants pretty travel photos? i keep seeing the 28-200 mentioned but then people say the 28-75 is better for blurry backgrounds and my head is spinning...