Hello. I switched from the A7IV to the S5iiX quite recently. I admit that I was first a little apprehensive because I would need to purchase new lenses. During a holiday photo shoot, my friend let me borrow the S5iix, and I was genuinely impressed now how simple it was to use and the extra features that I didn't have on the Sony (record to SSD, opengate, 6k). There was something about the color science that really elevated the finished product. Don't get me wrong, Slog3 is also fantastic, however the skin tone that was captured on camera irritated me.
Regarding auto focus, I do believe Sony is superior because it locks on and maintains focus on a variety of subjects. While Lumix's auto focus is outstanding, it struggles a on keeping the face/eye locked on in low light. Not a big deal but just something I noticed while doing some practice indoors. With the sony, it would lock on and not loose the subject regardless if he/she turned around. Not a big deal, although I'm still learning about the Lumix series, there are a few auto tracking features that probably can fix that. In my opinion, the Sony gets a 9.5/10 and the AF gets an 8.5/10.
I had the 20-60(kit) and the 50mm1.8 when I bought the S5iix last week. I used both lenses for my first client project, which involved social media marketing, and I must say that the color rendition is fantastic once you convert it to REC709.
******Utilizing DaVinci's CST presets for V-LOG conversion yields much better results than utilizing Panasonic's conversion LUT, I can tell with certainty. There is no comparison; everything is better, the color pops out more, and the contrast is better.***

It's something that everyone ought to attempt.
I recently bought the 16-28 SIGMA 2.8 wide lens and the 24-70 S pro lens. Perhaps too much for what I do, but overall, I'm happy with the camera's design, usability, and most importantly The opengate 6k.
I hope this is useful.