Gotcha, now I have a better idea of what you're trying to do.
Watching this video about looping in LMMS shows it can sorta be done, sometimes with some help from Audacity.
If you're adding in more stuff like VST plugins and vocals, you may want to try out Waveform Free, which I checked is for iOS also, so you get a full modern DAW. It's the same product as their paid full version, just like 2 updates behind.
For more premade loops, check out Looperman if you haven't already.
It's not free, but I think I under $20 for the program and all the upgrades, if looping and sampling is something you want to focus on, check out Koala Sampler. I downloaded it the other week and have been sampling vinyl recordings from YouTube, it has an AI stem extractor to separate the instrument tracks, and then chopping and looping that.
It has a built in simple synth now as well, and you can use a midi controller with it. Lots of videos are out there if you want to see how that works. You might be able to incorporate that into your setup.