I have also heard in some forums some people having issues with cooling their 6900XT but not only related to MSI. Even some reports from owners of factory fitted water blocks.
My 6900XTU Liquid Devil Ultimate which comes factory fitted with EK water block was also hitting 93-95°C although I have pretty good water cooling loop.
For me the solution was to open my card and replace standard thermal past with Liquid Metal and my max hotspot went to below 78°C.
At what fan speeds did you test this?
Using defualt fan profile or higher speed?
I had a few 6900XT fan cooled in my hands in the past.
If you increase powerlimit then temperature goes quickly to higher than 90°C.
What always helped was custom fan profile where fan already running at relatively high speed even at low temperatures and also please turn off Zero RPM feature in the drivers otherwise fan stops every time it has opportunity to do so thus temperatures are worst when you are Ocing the card.
Unfortunately, from my experience 6900XTs produce a lot of heat when you increase power limit with MPT and therefore not easy to cool without waterblock.
People who very seriously want to squeeze the best OC performance out of their 6900XT eventually end up by changing to water block.
One need but to test the card first. Some cards don't OC well at all. In that case water block would be an overkill.