@privet3711 its not uncommon to have 2000 in classical and 1750 in rapid. Usually you should have 100-200 points lower rating in each quicker time control, because of the inflation of the rating. 2000 in classical is easier to achieve for anyone who plays all time controls equally then rapid blitz or bullet. There are just more people that play faster time controls, thats why competion for higher rating is more.
If you have 2000 in classical you, however, should have 1800-1900 in rapid. 1750 is almoust 1800, but you should increase this a little more. If you could get 1850 in rapid then both of your time controles should be considered equal.
If you want to learn quicker time controls however to play better, just play a lot of them. Its all about getting used to it. Also you could learn time managment theory a little. There are some books that have that information, i read in 2 or 3 books tips how to control the time better. One is calculating how much time you have per move, other how much time you have until deep zeitnot(time trouble) - thats a situation on the clock where you cannot look for good moves, you can only look for moves that doesnt lose instantly. In that situation your whole game strategy changes. So calculate time until that and try to calculate time per move there. When analyzing games you can look - on which move you spent how much time, in tournaments, if judge allows, you can write after each 5 moves or so the time you have on the clock, but in lichess after each move computer tells what time you had, so you can see in what situations you think more and when less, and insert that into your calculations and look for those "critical positions" in your game - that you can predict - here you will need more time to think.
You can also create opening repertuare that needs less time to think about. Instead of Ruy Lopez, you can play 1.b3 - Larsens opening, instead of sicilian defense you can play russian defence 1.e4 e5 2.nf3 nf6 and get similiar position every game and save time thinking about that.
There are many tips on time control managment. Find some books on it or some articles on the net. Other then that just get used to it by playing a lot of that time control.