How to do multilingual seo

Please help me this because i am in a niche where completion is very low or near to negative and due to my research practice I find those topics which are literally untouched and every day thousands of that topics come in that now the matter is
I want to learn multilingual seo because a website with 70 days and zero backlink is taking 11k us traffic and he is in my niche but what’s he is implimenting is multilingual seo and I want to know about this so that I can also get that traffic along with multiple 1 da website topics in my niche and how I could do by topical authority and which I already have in 3-4 categories so please vikash guide me how to do multilingual seo or international seo blog with creating sun directory of my blog like https://www.example.com/fr and I am in gaming blog niche btw these research couldn’t be possible if you haven’t released the paid blogging course

Hope you help because there were no info into this and this is the biggest opportunity for me right now

If you have budget, then you can use GTranslate.io, it can create for you sub-directory. If you haven’t budget you can translate the that and publish it and the title in translate article add canonical URL, because Google will think it as duplicate content. Hope you it will help you.