This app was mentioned in 6 comments, with an average of 2.33 upvotes
This app will test you on every single aspect of about 6000 Kanji. There's thousands of practice questions and they offer sample papers for the Kanji Kentei - the test that native people can take to prove their Kanji knowledge.
It won't actually teach you how to write them, but you'll be able to drill in every Kanji really well with the app, and you'll constantly be drilling in context, so you'll learn tons of words in actual sentences. It's honestly the best app you can get I think.
One thing worth mentioning is it does have in-app purchases, but the exercises for the first 1006 Kanji are free so you can get tons of practice in before you have to get your wallet out, and even when you do it'll take you so long to learn 2300+ Kanji that it'll be spread out.
Do you mean this? It's my favourite Kanji app. You practice everything about Kanji, but in addition to that you get a lot of comprehension practice with the homonyms, antonyms and example sentences.
I use this app too for learning the stroke order. It's pretty great. The developer has other similar apps that test you on compounds and stuff and one that focuses on the Kanken from 6級 (5th grade) all the way to 1級, so this company can teach you all the jōyō Kanji and then like 3000 more.
For learning Kanji I mostly use this app and also this one:
This one doesn't teach the stroke order but it has exercises that cover all the things the Kanken tests you on like reading, writing, antonyms, homonyms, stroke order, etc. Best of all the reading and writing exercises have full sentences that only use Kanji that you should know in each grade, so it can get you reading very well.
There are in-app purchases though. You'll get all the exercises and a sample paper for all of the elementary level Kanji for free, then you have to pay a small price if you want an extra 12 sample papers for better practise. For the remaining Kanji you have to pay a bit more to unlock everything at once for each grade. Japanese reviews seem to complain about the price since they're having to buy the top levels close together, but for us learners we should be able to enjoy free for a long time and slowly pay for the rest. You'll know if you like the app or not long before you pay at least.
Apps for 漢検 are indeed the most promising direction. Specifically, this one has questions where you have to write words consisting of multiple kanji: https://play.google.com/store/apps/details?id=jp.co.imagineer.kanken.start&hl=en&gl=US
Not sure if these fit, but I got some nice tips from other threads that don't get mentioned too often. These are good for Kanji practice.
One of them is the Kanken Start app which has tons of free Kanji drills for the earlier levels, with paid content being practice tests, and advanced level drills (by that time, I think you'd probably need to be N2 or N1 level). The first level is 10.
Or this free Kanji writing app for elementary school students, which is also good practice.
In this app some questions require writing more than one kanji: https://play.google.com/store/apps/details?id=jp.co.imagineer.kanken.start
Also, this https://ankiweb.net/shared/info/759825185Anki deck has many questions where you have to write a whole word.