What tactical approach according to you would have helped the French team win the match?
With stars in almost all positions what different can one do really?
I don't think it's tactics necessarily (although a good coach would have done better with tactics) as much as I think it's the man management.
More specifically, you don't start all of your stars simultaneously against a team like Spain (that loves to have possession of the ball) because the stars don't like defending (generally speaking). It's why PSG had failed so much in the Messi + Neymar era (none of these 2 likes defending and running their assess off, they only want to attack, dribble and score, like the pussies they are) and it's why this PSG is seeing so much success.
For as much as I dislike Luis Enrique I will give him props for getting rid of the stars and building a team of young, not entitled (yet) players that love obeying instructions and running their hearts out. It's those players (along with a competent coach, obviously, at this high level of football you can't have one or the other, you need to be decent in almost everything: skill, stamina, coaching, mentality, etc) that will bring success.
In the case of Deschamps specifically, he was too weak to leave Dembele and / or Oliseh and / or Barcola and / or Doue out, to replace them with more mediocre players but which love running. In this French team only Rabbiot, Tchoumeny, and Kunde did most of the running and pressing, Dembele I never liked that guy (as a personality), he's always too cheeky and entitled, if you piss him off (and he gets pissed off quite easily) he will disobey you and do whatever he wants.
And Mbappe hates defending, I never saw him making a decisive (goal saving) tackle or anything, he just likes to stay upfront so he can break away and score... although, this could be Deschamps' instructions, in which case it's Didier's fault like I keep saying that he's not a good coach.
Not to mention that Mbappe is not a striker anyway, he's more of a winger, so a 4-3-3 system suits him better... although, 4-2-3-1 is not bad either for him, but in this case he should play as LW, not as a striker like he did against Spain...
Of course, it's very hard to leave players like Oliseh, Dembele or Doue on the bench and only play 1-2 stars at a time, it takes cojones and respect from your players, something that I don't think Deschamps has... or he doesn't have enough of anyway...
That's why Portugal failed too (Martinez was too big of a pussy to keep Penaldo benched, so Portugal has been playing with 10 men basically the entire tournament). But now that Penaldo is gone we will get to see a more efficient and successfull Portugal at the next Euros and WCs... although, if Jorge Jesus is the "new" coach like it's been rumoured then I don't trust that guy either. I've seen him manage Portugal before, and I've not been impressed...
But anyway, regarding Deschamps and France vs Spain, I genuinely don't know what Deschamps could have done since I'm not a great tactician either (nor am I directly involved in this sport), but all I know is that Deschamp is not a good coach. His luck - as I said many times before - is that he's always had a stacked roster at his disposal, but starting all of your stars at the same time but only having 2-3 players doing the running and pressing will almost never work against teams like Spain. I know this much.
And I tell you something.... if England beats Argentina tonight Tuchel will get the tactics right against Spain, he's a better tactician than Deschamps, so I will trust (and predict) England to beat Spain. The problem is FIFA, they seem hellbent on making Argentina win this WC (for political reasons related to Israel and stuff), so I don't see England winning tonight... at least not fair and square. I think that Argentina will get helped to win, which is sad because - if this happens - I will have wasted 2 months of my life waiting for this WC and investing my time and energy into a rigged competition...
But anyway, we will see tonight... but like I said, if England manages to beat Argentina I am 90-95% certain that England wins this WC because I trust Tuchel to nulify all of Spain's threats (which, by the way, in my opinion is not Yamal, I think Cucurella, Porro, Fabian Ruiz and Dani Olmo are much more important players for the Spanish team than people give them credit... I think these 4 players need to be neutralized first and foremost, and if you manage to keep these 4 players quiet - although, you should also not allow Yamal to roam freely either, obviously - I think England will do against Spain better than France did)