Comments
I believe this could be achieved by going to Feature management, and enabling the "Decimals for rounding precision in leave and absence module" feature? This will of course impact the entire leave and absence module for the given legal entity including the amount in time off requests. You can search for the Learn: Dynamics 365: Dynamics 365 Human Resources page "Configure the number of decimal places in Leave and absence" for more details.
In D365 the delegation is limited to workflow tasks. It would be great if another manager can be set as a full delegate / substitute user so that manager can also fulfill other responsibilities of the absent manager like for example submitting a time off request on behalf of a subordinate of the absent manager.Now this can be only done by Human Resources. Changing the reporting structure temporarily is not an acceptable workaround.