Hi Javi and welcome.
Could it be that you’re looking for the rule “Service check timeout (Microcore)”?
With this, you should be able to change the timeouts of services, including active checks.
If you use this option “Paramters for this service”, you can always check which rule is working for this type of service:
In the corresponding site you should be able to find all matching rules with active rule-set and default values.
Sincerely Kruzgoth