It is unlikely that Flick will be able to increase anything, since he refused new transfers, given the financial situation of the club. Injuries will happen in any case, and of course Real Madrid have much greater depth in the squad and the Real bench is very high quality, I think Real could make another very decent team with players on the bench. If Flick faces multiple injuries, it will most likely be an unfixable situation for Barcelona, but there is no need to think ahead, problems need to be solved as they arise. Barcelona has a good squad that can compete even with Real Madrid.
The club's financial situation is the most pressing issue currently at Barcelona. Because this club is currently struggling to restore its financial condition so that it returns to a more stable condition. So it is not surprising that last season Barcelona was not actively shopping for expensive new players. And very different from previous seasons. So I also don't feel surprised if this season Barcelona still doesn't make much movement in the transfer market. because they are indeed struggling for financial improvement. Hansi Flick is actually targeting several new players that he wants to bring in. And currently Barcelona itself is also starting to target Nico Williams from Athletic Club. But the condition of Barcelona's second tier players is not very good. This is different from Real Madrid, which already has a main squad and a second tier whose quality is beyond doubt. Real Madrid can be said to be the club most prepared for next season.
Barcelona is facing a very difficult situation right now and with the fact that Flick is not making new signings even makes it further complicated for the team. It's not like Barcelona don't have a nice squad to compete against Real Madrid, if they don't and think they would not have even ended in the second place last season. For now, due to financial constraints Barcelona may not be able to meet up signing high profile players so it's obvious Flick have to manage the ones available a create a better team but it will require a lot of hard work and concentration to be able to achieve that because since the Madrid team have even strengthened the team more it will be difficult for Barcelona to match up with Real Madrid because Real Madrid have got better financial system and better squad so they lack nothing but Barcelona should just make sure that Real Madrid don't give them much gap as they did last season so that if Madrid makes any slight mistakes Barcelona can take advantage of the opportunity. At least if Barcelona wins the LA Liga it will create some financial aid to the team to be able to exploit more in the upcoming seasons.
Even if Flick is targeting on getting new players to the team, can the club afford those players? Nico William was a player that performed very well in the just ended UEFA EURO tournament and due to his performance in the competition has further increased his market value so I don't think Barcelona will be able to meet up his transfer conditions. Nico William might even decide to move to Arsenal since Arsenal is also interested in the France International and since he is currently playing for Athletic Bilbao which is also in Span he can consider moving out of Spain to England should Arsenal meet his transfer requirements.