In this chapter, the Israelites continue sweeping up Canaanite towns after the death of Joshua.
This chapter appears to be an introduction to the immediate history before the Judges period. The first thing I noticed about this chapter is that the chronology is a bit weird. Verse 1 places us firmly after the death of Joshua, so at first glance you'd think that everything described here happened after Joshua died. That does not appear to be the case, because among other things, the conquest of Debir is also listed in Joshua 10 and the story about Caleb giving his daughter Achsah to Othniel is also repeated from Joshua 15 (although that story from Joshua 15 has an uncertain chronology of its own). Some other cities in this chapter are mentioned in Joshua 12, which again seems to imply that they were conquered during the lifetime of Joshua (examples: Hormah, Bethel, Hebron, Jerusalem).
However, other cities are almost definitely new and post-date Joshua. For instance, Ashkelon, Gaza and Ekron are specified called out by the LORD in Joshua 13:3 as cities that have yet to be conquered by the Israelites, but in this chapter they are taken by Judah.
So I think this chapter has two purposes. First, it is reminding us what happened during the invasion with Joshua, but it is not precisely aligned with the book of Joshua. It includes some conquests that were in Joshua and some that weren't. I wouldn't go so far as to call it an inconsistency, but it seems to indicate that Joshua and Judges are to some extent separate works. That said, there is still a lot of deliberate continuity between the first book and the second, because this chapter directly references the death of Joshua, which happened in the last chapter of Joshua, and this chapter also includes the story about Caleb taking Debir which was also in Joshua.
The second purpose of this chapter is to establish the numerous Canaanite cities that were not captured by Israel, as this forms a significant part of the Judges sin narrative. If you read my introduction to Judges, I talked about the Israelites' persistence in sin as being a major cause of the Judges cycle. The Israelites were frequently warned against allowing the Canaanites to survive in the land because they would ensnare the Israelites into sin, like what happened in Peor (Num 25). They were again warned against this in Deut 20, and first started allowing Canaanites to survive in the land with their careless oath in Joshua 9. However, Joshua 13 lists many places that Israel did not conquer, and while they take some of the cities in this chapter, verses 27-36 list the many places that Israel did not conquer within their borders. Unfortunately, Israel is shortly going to pay a heavy price for not driving out the Canaanites.
There are a few other short stories in this chapter. The first one is that Judah and Simeon assist each other in taking their respective inheritances. If my readers remember, the inheritance of Simeon was placed within the borders of Judah because Judah was given too much land for their people to occupy (Joshua 19:9). These two tribes will be closely related such as here when they fight on each other's behalf.
But already we can see there is a difference in how Israel is fighting now. Joshua dismissed the national army, and each tribe is fighting for their own inheritance alone, rather than collectively. Ostensibly, this is because Israel conquered most of their objectives and everyone has been given an inheritance. More practically, this is probably because Israel simply doesn't have a national leader who can organize all the tribes together. It reminds me of the many times in the Pentateuch where I pointed out how various passages are designed to reinforce a sense of national unity amongst the tribes, repetition of the number 12 and so forth. All of those times I said, Moses is trying to establish a sense of national unity because the tribes otherwise do not think of themselves as a nation. Now that Moses and Joshua are both gone, that facade of cohesiveness largely disappears. That is what we are witnessing here, the disintegration of Israel's national identity.
Another short story from this chapter is that the Kenites live in the land with Judah. This is probably referring to the descendants of Hobab, the son of Jethro (a.k.a. Reuel), who was implied as going with Moses in Num 10:29-32. So apparently Hobab did go with Moses, and now there are a family or small clan of them residing with the sons of Judah.
The last short story I will mention is that in v. 34, we learn that Dan is mostly unable to take their inheritance. Many of the tribes are struggling to drive out their foes, but in the case of Dan they are being substantially defeated. Later in Judges we will learn what the Danites choose to do when they cannot take the inheritance they were assigned.