As a teacher, I believe that nothing replaces one to one or group interaction. However, if you are too busy to attend lessons or meet with a tutor, online learning can be a great subsitute.
There are many Youtube videos and websites and mobile phone apps available to help you learn. Some are very good, some are not. Some sites are accessible with no fee but some sites require subscription and a small fee. To save you time finding the best sites or apps, here is my selection:
Free desktop and mobile App: Duolingo
Free website: The French Experiment
Fee paying website: Learn French with Alexa
YouTube channel: Learn French with Alexa Polidoro
Online vocabulary and grammar exercises: French Institute
I hope you will find these links useful. And if you need a bit of inspiration, you can watch this video: Learning French in 6 Months.