Apple is pretty quick to kill torrenting apps, but you do have a few options if you're on iOS.
https://www.seedr.cc/ (My buddy uses this, I don't use iOS, so can't comment)
https://www.torrentsafe.com/ which will let you paste mag links. They also have extensions for Chrome and FireFox.
https://bitport.io/ Never used em or know anyone who has, but is another option.
There may be more, but I've hit my wall with iOS related stuff...lol
Apple bans all torrent like apps from being used in the App Store. a quick Google search shows this is one site that can be used to paste a magnet link and it will download the file(s) directly to your device.
I can't really say for Seedr, but I do know that torrentsafe is a good alternative. It has a solid free plan that I've been using for a while and a pretty affordable paid plan. Here's their website so you can see if it fits what you're looking for