It would be interesting to know what specific tasks are assigned to Flick, but this is classified information (at least for now). Barcelona cannot publicly admit that they have no goal of winning La Liga (due to their status) so now we can only guess what they want from him. If we draw an analogy with Xavi, last season they expected any two trophies from him (even the smallest one like the Spanish Cup). It seems to me that the target level for him is set as “no lower than second place in La Liga and no less than the quarterfinals in the Champions League + some title.”
La is not for some random mediocre team. Xavi Hernandez was relived from his duties because the board simply want what's best and they've seen a competent coach which they probably solve the problem. Barcelona newly appointed coach, Hansi Flick is currently in charge we should expect the very best from him and Barcelona next season.
Since Handy Flick will be in charge at Barcelona from next season then it must be hoped for the best for the team. Although we have seen Xabi in charge this season but he wanted to give his best for Barcelona but did not succeed in La Liga and also in the Champions League. But we can expect to see Barcelona at a better level from next season as the team is not in such a good situation at present. If the new coach comes in and can follow up on the good performances of the players and bring young players into the team then surely the team is likely to be full again. So I can expect that next season the Barcelona team will definitely be more competitive to compete with Real Madrid.