Like I posted in the GDT, they're a team so well built that they can play any sort of style and still win. I think Tampa is the only team in the NHL today that can claim that, I don't even think Vegas falls in that category.
There aren't many teams that can do that, hell even a lot of cup winning teams couldn't even do that. A lot of cup teams are built to 1 specific attribute that they're so good that they can just dominate with it. Look at the cup winners before Tampa, I feel like those 3 teams (St. Louis, Washington and Pittsburgh) just maximized 1 or 2 attributes and rode those to the cup. But Tampa has maximized seemingly all of their attributes, to the point where they can win any sort of game that may arise. The 2016-2017 Penguins, 2018 Capitals and 2019 Blues didn't have the extreme versatility that the 2021 Lightning do.
The 2019 Blues wouldn't have won the cup had they had a matchup that turned games into end to end offensive games. The 2018 Caps wouldn't have won the cup had they had a matchup that turned games into all speed and little physicality matchups. The 2016 and 2017 Penguins wouldn't have won the cup had they had a matchup that turned those games into slower, physical games. With Tampa, I think they can win with any of those changes just because of how well built they are.