The i9-9900, if kept at 65W TDP and run in mainboard that adheres to those standards, should indeed be fine; if, however, it is plugged into a Z390 that has power limits/TDP constraints/, and turbo duration limits all dsiabled, MCE-enabled, etc., it will run almost like an overclocked 9900K, minus perhaps 100 MHz, and, likely overheat...and quite quickly.
The 9900, given it's 65W TDP, should only run at all core turbos of 3.5 GHz or less after 30-60 seconds....; if it keeps higher clock speeds (4.6-4.7 GHz would be a dead giveaway to power limits being disabled) beyond that timeframe, then the mainboard in question is running with turbo duration limits disabled....
For the original poster...what Asus Prime mainboard is this?