Being a newcomer isn't really a disadvantage. Nintendo took over the North American console market with the NES as a newcomer.
You say that, but it really is hard to imagine that a newcomer would just come out today and outsell the PS5 and Switch out of the gate.
Times have certainly changed, so yes, it wouldn't be possible today like it was back in the day.
The 1970s, 1980s and early 1990s were full of companies who tried their luck in the console business, but by the late 1990s just about every notable company had given it a shot and failed (except Nintendo, Sega, Sony), so the only big new entrant after 1994 was Microsoft in 2001 and nothing since.
Corporations like Amazon, Google and Apple have lots of money, but no expertise in game making whatsoever. That makes them different to Nintendo and Sega who had experience in making arcade games before making their own console, different to Sony who were already a game publisher on consoles, and different to Microsoft who gathered major experience in the PC market.
The PS1 also had the benefit of a ~18 month headstart over the N64, so this allowed Sony to establish a game library and lower the price of their console by the time Nintendo was ready. If I remember correctly, the PS1's headstart amounted to only ~8m shipped by June 1996, so it wasn't a winner right out of the gate. Sony needed time and they got it, so they had sorted out their major issues by the time Nintendo showed up with their own early console struggles, most notably the N64's release schedule that was a trickle.
Throw in Sony's widespread moneyhats that surprised both Nintendo and Sega, and it's easy to see why the PS1 got rolling after a rather rocky start. A notable side effect of the moneyhats was that the developers who went exclusively with Sony tried to convince other developers to go with Sony too, because the more successful the PS1 would be, the more successful the moneyhatted third parties could become. Final Fantasy VII stood at the center of all this, but it must be noted that Squaresoft as a whole went exclusively to the PS1, so it wasn't just about one game, but the entire publisher with its full portfolio of IPs.
Sony leveraging their other divisions to subsidize the PlayStation business early on (console sold at loss to offer better technology at a lower price than the Sega Saturn, moneyhats for third parties) was not only an aggressive strategy to get their foot in the door, but also an absolutely mandatory one.