Yes, it's possible. For me it went like this.

1. I learned enough vocabulary in a very short time to be able to more or less be able to read with the assistance of a dictionary on an e-book where you can click on a word. I spent ~2 weekends of Duolingo 8 hours a day, but I'd use flashcards in the future instead of that. It sounds a bit crazy in hindsight, but I feel like it was easier to stay strongly motivated for a short period of time than drizzling the words over a period of time. All other attempts where I did not do this, failed.

The limit of learning words for me is ~50-200 words per hour if using flashcards. It depends a lot on the language and how similar it is to the languages one already knows. 200, if it is similar to my native language, ~50, if I don't know anything similar at all. I'm also almost guaranteed to forget 80% of the words, if I don't use them in the next day or two, but its possible to cram a lot of them very fast and then move on to stage 2 to use them.

Important catch (for me at least), is that I can remember nouns far more easily than verbs or other more abstract/structural words. Those absolutely need to be in a sentence when learning. There's pretty much no point for me in trying to cram them on their own. I just cannot remember them in isolation at all and also which words they are used with differ per language anyway. Eg "to put" won't necessarily be used for all nouns in a different language even though a dictionary might say that's what it means. The good side is that knowing the nouns helps a lot in deciphering.

2. After the initial cramming I read a couple of short/simple books over some months in the evenings before sleep. I tried to listen to videos & to talk to some people a bit now and then, but it was extremely hard and boring as I understood too little. In hindsight I should have listened more to videos, but the good ones are surprisingly hard to find, if you don't live in the country that already speaks the language one is learning.

3. I tried several options for getting conversational after that. First a private teacher who knew the language well, but was not experienced enough (a university student) to teach somebody who tends to use weird methods for learning. She kept getting confused about why I understand complex words that were basically the same in English, Spanish and other European languages, but why I struggled with the basics when talking at the same time.

I also tried some learning groups. They were fine, but it's very difficult to find people at the same level after starting to learn a language and not following a preset path. I was felt either far ahead and far behind at the same time.

Eventually I found a native speaking private teacher who had years of experience. He could make the classes interesting and after ~1.5-2 years of talking with him 1-2 times per week for an hour about pretty much anything, I can hold a conversation and handle things in general. I still kept learning vocabulary in parallel and I'm not quite fluent as I don't use the language daily, but I'm not too far off either. Overall it took maybe 2-3 years, because I wasn't very consistent at the beginning.

If I were to change anything, it's getting the private teacher way sooner, skipping the learning groups entirely and using flash cards + asking for verbs/structural words as parts of sentences from either the private teacher or finding some other resource for it to start with. Using AI is possible too I guess for that purpose, but only with more common languages. Most AIs completely mess up my native language and invent words that don't exist, so I wouldn't trust them much when learning.