DiRT 4

If you're struggling to get into the top two tiers on the standard daily events wait until there is a Delta Daily. These semi-regular community events only have two tiers so by default you finish in the top two.

I had the achievement unlock this way - wasn't expecting it but not going to complain. Be aware though that there is also a separate achievement for finishing in the top tier of a Delta Daily.

This achievement requires a bit of skill, but should be doable for most. Inside of the Community Events hub, there is an item for a Daily Race. This changes every 24 hours and can vary in vehicle choice, location or track conditions.

You must complete the race, and ensure your time is logged. Check in the next day (the previous day's event needs to have closed out) to see which 'tier' out of 4 you ended up in.

Make it into tier two or higher, and you should have the achievement pop.

Obviously, this is dependent on your skill level, it took me three daily attempts to finally land on one I was able to get into Tier 2 for.

FYI
In August/September 2021 Codemasters broke something with Racenet for Dirt4 players on Xbox. See https://imgur.com/gallery/gS2DaPo

Xbox players will not be able to connect to Racenet until Codemasters fix their problem, (PC and Playstation are still fine). All of the Event achievements* are affected and if you need them to complete, complain to Codemasters on their forum, reddit, twitter and via their customer service email. They will tell you to go troubleshoot your connection but see the imgur link above, literally no-one on Xbox can connect to Racenet in Dirt4.

*achievements Delta Force, Flavour of the Week, and Dirty Dozen