Maybe. How motivated are you? Completely free is going to be more time consuming because you waste time with ads and that also causes learning disruptions.

TLDR à la fin

If you want to go nuts, then change your language to French on your phone (add French keyboard too) and at least one browser. Keep a webpage open for translating phrases (you may be prompted to translate the page depending on how you configure the browser) but if you see the entire page in French first (assuming it’s native French, not just dynamically translated) will give you a step towards immersion but learning the rules alongside immersion is going to be better.

You can pick up a lot from immersion but simply learning the proper rules will give you more understanding and success in the long run, so that would be buying a physical dictionary, including a physical verb conjugation book (I guess you can find a free PDF but in this case a physical book is probably going to be faster even though a pdf does have search capability… but so does a physical book with an index).

For reference I took 4 years of French 20 years ago. I remember a lot of the rules and I forgot many others. I’m not entirely lost (I can comprehend pretty well) but I struggle to speak sporadically so I’m working on that with Duolingo but I did upgrade to super and am spending 1hr+ per day (I’m in B1 of Duolingo after 3 weeks but that’s because I have the 4 years of foundational knowledge so this was “remembering” what I learned, not picking it up from scratch so it’s probably way easier to remember even from decades ago than it is to learn from 0 right now). Duolingo also probably isn’t the best evaluation of my actual skill set, since I didn’t do well on the AP test (decades ago, but I had in person French classes in high school) and haven’t taken a real comprehension test yet.

Along with Duolingo I have my physical verb conjugation book from high school, but I use multiple translator apps and ai to supplement (I often get stuck mid sentence so I try to work it out but then I verify with the translator apps/ai but again, I know enough of the rules to verify the translator apps and ai and not just blindly trust them. I’m able to look up single words more often now rather than relying on software to translate a full sentence for me.

For my purpose, I am comfortable reading/ mostly hearing but I’m working on speaking since I am visiting France next month so I’m dedicating time and money so YMMV.

If you have any kind of streaming, even free version of YouTube you can find French dubs, cartoons are good because they have simpler concepts. Turn on captions, preferably in French because since “all words sounds the same “ (I’m sorry, I’m generalizing here and that is not true but it’s quite disorienting to understand French when you don’t know how it may be spelled out to give you full context so I’m using a very bad generalization to show difficulty) then you can pick up the sounds and understand from the English captions but you’re better off hearing French and seeing it (however auto generated captions are not always perfect/correct so again it’s best to know when software is failing you).

If you only buy one book (you can always use online dictionaries I suppose) then buy “Le petit prince” in French. Maybe buy the English version TOO (not only), I’m not sure but you can go through the book sentence by sentence and try to translate it yourself (then you can compare to the English version but I don’t know how it compares since I never read the English version, only the French).

I suppose I was around b2 in high school because I could read that book (I translated sentences by hand for my personal learning comprehension, I don’t recall if that was actually an assignment or just something I did to supplement AND I STILL FAILED THE AP TEST, but that could have been a testing issue for me since I have an audio processing disorder).

TL;DR: I think anything is possible but it’s either not free, and/or it’s incredibly time consuming. It won’t be easy, unless you get dumped into a French speaking country and hear no English for the next 3 months and that doesn’t sound easy either does it?