Even if that were true (it's not imo, they have bigger problems from the top of the club all the way down), we have been in that position many times until recent years, & it's extremely difficult to get right, & you could argue that case for almost any of the top half sides, 3 or 4 quality players will revolutionise most sides.
Of course Utd will be in a stronger position to try to get it right, despite their vampirific owners they can & will throw shitloads of cash at their problems, which in footy is always a huge advantage.
Look at it this way though, take, say Haaland, loads of top clubs sniffing round him, can you see him choosing Utd over City, us? Even Arsenal or Chelsea look a better environment & more likely to get into the CL.
So they're left with things like massively overspending on Kane, & offering obscene contracts to an aged & past his prime De Gea cos they can't or won't try to, attract a younger quality keeper.
They're a fucking shitshow from top to bottom, & there's no easy fix, they'd have to get in a top manager, & then give him the funds to buy at least 4 younger top quality players all at once to even start to arrest the decline, & they don't even have a capable DOF in place to do that kind of long term planning.