I speak several languages including Italian.
I have learned most of the languages I speak living in the country BUT you can obviously learn a language without moving abroad. To do that though you need to integrate as much of that language into your daily life.
With kids it’s known that ideally they should listen or be exposed to the language at least 50% of the time, on a daily basis, but for adults I would say there is probably much more exposure needed.
Swap your Netflix to Italian. Not English with Italian subtitles. Italian with Italian subtitles. Why? Because you can guess most of what happens and is said in a movie based on what you see, and by hearing and reading the same sentences all of the time in similar scenarios you will pick them up very quickly.
Start by your favorite movies and series to ease you up if you prefer but don’t fall into the trap of listening to things in one language while reading in an other because your brain will focus on what you already know (your own language) and you will pick up very little.So Italian voice over with Italian subtitles. Read books in Italian, start by books for kids and then move up little by little, also buy yourself an Italian cookbook in Italian and get into the habit of learning to follow recipes in Italian, translate what you don’t know and then you will see how quickly you learn all the vocabulary linked to food and cooking, go to language exchange meetings or find your local Italian expat community and ask if some would let you practice. Give yourself daily challenges, learn new vocabulary daily, give yourself random excercise such as “research and do a presentation about a historical figure” you don’t need a public it’s about you learning to collect information in Italian, you reading about specific topics in Italian, writing about them and learning to speak and pronounce the words. Ideally find a tandem partner an Italian who would love to learn English properly so you can both correct each other.
Pretty much just integrate Italian to your everyday life & even get into the habit of naming things in Italian for yourself be it going through the word in Italian for each item of clothing you are wearing, food your are eating, item you are buying.
Learning a language late in life isn’t impossible but it does require dedication and quite a lot of repetitive work.