Yakuza Kiwami

Legend difficulty for the most part shouldn't be too difficult if approached correctly.

-Be sure to start Legend difficulty in NG+ mode. You will carry over all of the abilities Kiryu acquired throughout the game. Tiger Drop can make most of the boss encounters really easy and fast. It can be acquired through Komaki training (it's 10th upgrade you get). I would suggest completing Climax Battles before starting Legend difficulty. You get used to some boss patterns like Atobe, which makes it easier to fight him on Legend.

-Chapter 9 car chase is usually a part that people find really difficult. It will probably take you couple tries to get it so you should be ready to spend at least a hour on this part, probably more. There are couple guides on youtube, personally I used devilleon7 video for this car chase:

During the sequence don't aim for headshots, aim for the center of the circle. Headshots don't have anything to do with critical damage. Aiming for the centre of the circle will deal more damage.
The truck has 4 stages:
-Stage 1: Focus on the second guy (to the right) and kill him
-Stage 2: Focus on the cars, they will stop coming after a while. Use your focus on rockets to take them out
-Stage 3: It's probably the hardest part. I focused on the guy on the truck and used focus to get motorcycle guys to not shoot me when they went orange.
-Stage 4: I started with focus, then continue to shoot and just about when he was starting to charge again into focus to break his charge. I did duck once in the car but you could kill him before his second charge if you are accurate enough.

-Last part that people had difficulties is a helicopter pad fight during the last chapter. I didn't really had a hard time with this, I would suggest to get couple strong weapons to do quick work on the 2 guys with the boss. If you have equip sacrifice stone. I also stocked my inventory with toughness infinity and Staminan Spark bought at Casino since you can easily acquire them there. I had quite a bit left so full inventory should be enough to get through this fight.

-Lastly, couple tips I used. I usually played with combination of Rush and Dragon style and using Brawler on occasions. You can build heat quite easily with Rush and use that to execute heat actions. I didn't use much weapons, just guns of other enemies that were dropped. I didn't use a lot of Beast style because most bosses are too fast for it, I only found it useful for groups of little guys, but even at those times Rush style worked well enough.

If you are having any problems, hope you find this useful.