One good thing for Barcelona is that they still have their games against Atletico Madrid and Real Madrid, meaning that if Barcelona beats these two teams, then we could probably see them do much better without a doubt. The gap is still quite large though, 4 point difference isn't really that small. Of course there are MANY games in between too, so they need to do fine during that time as well, they can't just lose points to bad teams over and over again, they keep doing that and the result isn't good.
Now that the gap is 4 points, I guess if they can keep winning enough, they could probably get back to leadership, but it would require them to do much better at the league, just like how they were at the start of the season.
You are right, Barcelona still has games against Real Madrid and Atletico Madrid in La liga. So, for example, Barcelona continues to consistently get the full 3 points in every match and maintains the point difference with the 2 teams above it until Barcelona's match against Real Madrid and Atletico Madrid arrives. So the matches against Real Madrid and also against Atletico Madrid will be matches that Barcelona can make good use of to gain points. Because as we know, currently Barcelona has a 4 point difference with the top team in La Liga, Real Madrid. So, for example, Barcelona can continue to win, including against Real Madrid and Atletico Madrid. It is certain that with this, Barcelona will definitely be able to return to being at the top of the Laliga standings.
But even so, it will definitely be quite difficult for Barcelona to get the full 3 points in the match against Atletico Madrid. Because in this upcoming match, Atletico Madrid will act as the host. So it is certain that with this, Barcelona will receive extraordinary pressure from the fanatical Atletico Madrid fans. This will certainly affect the focus of the Barcelona players, so it can result in inaccuracies in carrying out strategies. But for the match against Real Madrid, I think this time Barcelona will have an advantage. Because in this match Barcelona will play the role of host. So it is certain that Barcelona can have more freedom in this match to beat Real Madrid. Because even at Real Madrid's home ground, Barcelona was able to beat him. Therefore, Barcelona will most likely beat Real Madrid again in the upcoming match.