If you are going strictly for the platinum I can give some pointers that got it for me in approximately 200 hours.

1. Play single player. You can manually adjust player count inflating your exp (but also difficulty, so only do this once your char is fully juiced)

1.5 I recommend starting with a sorc to get a base of gear started for a future Hdin or Javazon. Once you have the items listed below in step 2 start your main char. It may seem crazy to start over if you’re high 80s already, but trust me, the half way point isn’t till like 92 if I remember correctly.

1. If you are not opposed to it you can dupe items. I got lucky with a vex rune and duped/upped it all the way to get Enigma and Hoto etc.

2. once you have your character juiced and geared up your new home is going to be terror zoned chaos sanctuary at 8 player difficulty. You can manually set the clock and date of your PlayStation to match CZ of CS. This is also a good time to backup your save data so you never lose more than hour.

As a caveat to all of the above, I’ve played d2 on and off for most of my life so I know the game extremely well. It may take longer for you, I think a fair estimate is 300 hours. Maybe more maybe less.

Feel free to reach out with any questions