F1 24

These are small random challenges that appear during races in Driver career mode. Usually about lap 3 or 4 of a short race and can be challenges like 'beat a lap time' , a tyre wear challenge. Just complete 25 to get the achievement.

Dynamic Objectives are given to you by your race engineer during the race, such as hitting a specific target lap time. They should come naturally while you are playing career - for me personally, I haven't had any of these assigned in My Team, only in the Driver career so I'm unsure if they are actually given in My Team - but in a 10 race Driver season with an Icon, I got one in every race.

But if you are in a hurry to unlock this, you can cross the finish line and complete the objective and then use a flashback to rewind a bit - the game will give you credit again when you cross the finish line again. I ran it up from 40% to 100% in the Australia GP by completing the objective, using the flashback to put me halfway between the last corner and the finish line, and repeating.