You should use the order that the company expects in the dropdown
That should be the order that makes most sense to your users based on their context
There is no 'best' way or simple standard other than what is most suitable for your situation based on the business requirements.
The most suitable approach will depend on many factors.
Context will also determine sort direction.
There are several general approaches:
Most familiar in many cases. Can present issues for multiple languages
Simplest to implement if data is displayed using a numeric index
For example show today, tomorrow, next day-1, next day-2
Uses data based on other characteristics that lend themselves to grouping items based on their characteristics, e.g. all 'saws' are listed under a 'saws' group even though their name may start with 'ragged saw', 'large saw', 'ban-saw', etc. This is often combined with Subgroups.
Sometimes there are major categories, e.g. country and then subcategories, e.g. state and to capture state it is helpful for users when the state dropdown has this tree structure. This method can include various of the other approaches for then sorting the data within both the main and children lists.
Can be many different forms. One is that the top 'few' common options (1 to about 30 or so) are listed at the top and then a large number of less frequently used 'other' options are listed below them. You see this frequently used to for 'United States' as the top of a country list instead of at the bottom where alphabetic sorting would place it.
Are you or your senior knowledgeable about how users use the product for their context ?