In iOS you can change the quality of the video your device records, which is essential if you're planning on uploading to an online platform, as many if not most have a maximum file size of 500 MB, at 1080p you'll easily exceed that just a few minutes of video, you can resize it afterwards, but... that's a hassle, why not reduce the size of the videos you record, as you record them?
At the default recording setting of 1080p you can eat up a load of storage space, and struggle when trying to share it online, when even 10 seconds of video could be 100MB- that's HUGE.
My advice? Change it to 720p, that's more than enough; here's how: