A lot of people recommend Tae Kim’s guide. I personally didn’t like it but everyone’s different. The grammar points are presented one by one with simple explanation, but IMO it suffers from over-simplification sometimes, and there’s a lack of exercises.
If you’re comfortable with linguistic terms and aren’t worried about jumping into the deep end, Imabi is a good choice. The content is all top-tier and in depth, having been written by a linguist, but the site isn’t very well organised tbh. Also, a lack of exercises.
One resource that I’m currently really enjoying myself is Bunpro; it’s an SRS like Wanikani where it gives you a grammar point with a small explanation, links to a few different resources that also explain it, and then has you review it over time by filling the blanks of example sentences.
Some popular youtubers with video explanations of gramma include Cure Dolly and Japanese Ammo with Misa.
If you do eventually go the textbook route, the usual choices for that are either Genki or Minna no Nihongo. Other options include Japanese for Busy People, Yookoso, Japanese: the Spoken Language, Japanese the Manga Way, and Japanese from Zero; each of them obviously with their own pros and cons.
Personally, I would recommend getting your base down as quickly as possible with something like Tae Kim, and then diving headfirst into native content like manga and simple novels. It’s way more fun and teaches you via immersion. At first it feels somewhat like throwing yourself full-speed at a wall and hoping you can cling onto one of the bricks, but it gets easier the more you read, and the book clubs in this community are great for collaborating and discussing any problem areas with other readers.
Somewhat related to the above is Tadoku and graded readers. The idea is to read as early as possible, and not actively study grammar, but infer it from context. I can’t pretend I know how successful that is, but it’s an option nontheless.
Good luck!