Judging from last gen I doubt there will be parity. We have seen countless games that ran better or had different resolutions. And exclusives will look great on either of the consoles. History repeats itself. We'll see games with slightly different performance, Xbots boasting about spec superiority and Ponys calling out lazy devs. Unless you can tell me a reason why it would be any different next gen.
The difference should be that XB fans had a hard time praising XB1 because when it came to gaming, it really had nothing over PS4. That partially flipped when XB1X launched though, but PS4 Pro still had a clear games and price advantage.
Now you're going to have games, that to gamers in the flesh, will be slightly more visually pleasing on XBSX across most titles, but will be slightly faster and snappier on PS5 across most titles.
One group will praise the visuals, the other will praise the speed, when in reality, the difference between both will be minimal most of the time. A write off or a wash basically. That won't mean each console has small advantages, but what's going to matter are the games, services, and prices.