No, there is not dafault pagination in the API.
It is on your side to request the API so that it may not return too must data.

I actually want to get all the tickets, so I'm going to use the '../projeqtor/api/ticket/all' endpoint. However, it returns too much data. How can I request the API in a way that avoids returning an excessive amount of data like pagination or make it take less time as it is in projeqtor it self ?
                HttpResponseMessage response = await _client.GetAsync(apiUrlProjeqtor); // here where it take a lot of time 
 

As previously answered, you must manage the pagination on your side.
For instance use the search option to limit the query.
Example :
search/id100 and id<=200
And so on