I figured the filter was manually automated but I got kinda lazy haha. I was using Serum so I over embellished a bit; took a supersaw with super low detune value, stacked it w/ a clean one, ran it through a formant filter (with just some slight modulation on the shape), slapped an LFO in envelope mode with a quick slope up but a long duration and slammed it into some tube distortion to give it back some edge (and them a small low pass to remove some of the new extra harsh high end).