If you're looking to learn how to play a character in whatever fighting game you're interested in and are feeling like your understanding and effectiveness with them is limited based on in-game tutorials, mission modes, command lists, and messing around yourself, it can be helpful to look for community resources. Other people playing the game and character before you have likely written about them already. Sometimes a character's gameplan is not as straightforward as it seems, or moves might have weird properties that aren't obvious.
Here's a list of some, in case you haven't about them. Keep in mind that these are community resources, nobody is being paid to write or edit them and I'm not being paid to shill them. The depth of coverage varies by site and by game, and even within that, by character, but the basic information on these sites is solid!
Dustloop is focused on Arc System Works fighting games- Granblue Fantasy Versus, BlazBlue, Guilty Gear, Dragon Ball FighterZ and many others. The more popular games have detailed strategy and matchup pages.
Mizuumi covers many "niche versus and fighting games". you can find Melty Blood, Under Night, Vampire Savior, Arcana Heart, Skullgirls, Samurai Shodown, Thems Fightin' Herds, Umineko Golden Fantasia, Idol Showdown, and so many more on this site, it's seriously amazing how many niche games have stuff written up on here.
SuperCombo is focused on Capcom games- the Vs. Capcom games and Street Fighter in particular. it seems like their SF6 coverage has been really good so far.
Dream Cancel covers King of Fighters- their KOFXV stuff is good from my experience.
This Tekken 8 Library spreadsheet has a lot of good beginner information for Tekken 8. It lists a selection of key moves as well as some easy starting combos, as well as a list of different punishes! Really recommend checking it out if you're new to the game! Wavu Wiki is still being worked on and great if you're looking to go deeper.
If you are an experienced player and look at these and think "Why doesn't this page talk about xyz on my character?"... Add that shit! As long as it's not WRONG, any information on a page is better than nothing being there. And people are much more likely to touch an existing section up than they are to start a new one. You could really be helping other players out!
If you know of any others for a game you play, feel free to add them in a share of this post or the comments! (Unless your information is on a Discord server in which case please put it somewhere else normal please)
edit: http://replaytheater.app is a great database of match footage for various games. You can filter by characters, players, or even specific matchups.