I hope you got a good deal on that board. The prices I see are around $175...for an 8-phase board that lists DisplayPort like it's a special feature?
Meanwhile the Gigabyte z390M Gaming is only $145 with a 10+2 phase design.
Either way the arch is still the same as Coffee/Kaby in terms of overclocking so the guide will still work just fine:
Overclocking with XTU is going to be about the same as using the BIOS as far as the multiplier/vcore procedure goes. You can use it to get into the ballpark but the fine tuning and final OC need to be in the BIOS to be stable.
If you're a noob you shouldn't be overclocking, you should be educating yourself on how to to it. If the BIOS is beyond you I don't think you can call any OC "stable"...especially since you're using XTU to do it.
There are loads of stress tests out there but the only one that's ever gotten be stable enough to run every game and program I use without issue is Prime95. You should ignore AVX to start with by using v26.6 as it has no AVX. Once you get your core, cache and ram 100% stable then you can take the time to find your AVX offset.
None of this is meant as an insult but knowing what you're doing is a critical part of doing something...if that makes any sense. Also, I'd punt the board and get a better one if you're overclocking. A stock 9900k (just the CPU) is capable of pulling 200w under an AVX stress test, a little vcore could easily make that 250w. MSI also has a bad track record of making some really crappy boards in comparison to the competition. They make some good boards too but I really wouldn't buy from them if there's another option.
People were complaining that Asus was selling 8 phase boards for over $150 with coffee lake so this MSI board is seriously whack for the price. The additional phases on other boards handle more power but they also provide more stable power to the CPU. Most people that switched from 8 phase boards reported stabilizing with much less vcore and in some cases were even able to get to the next multiplier...and that was with an 8700k, now add 2 more cores and 4 more threads plus more cache to the mix. For the price the board is a huge rip off IMO.