is calculate field using geodesic

[StevenSchwartz1]

when using calculate field are the comps using geodesic or planar methods?

[DanPatterson]

you can access geodesic using arcpy in field calculations,

Geometry—ArcGIS Pro | Documentation 

for example 

getArea ({type}, {units})
Type: PLANAR measurements reflect the projection of geographic data onto the 2D surface
(in other words, they will not take into account the curvature of the earth).
GEODESIC, GREAT_ELLIPTIC, LOXODROME, and PRESERVE_SHAPE measurement types may be chosen as an alternative, if desired.

but if you are calculating geometry attributes, there are options to do so explicitly in several tools, for instance

Add Geometry Attributes (Data Management)—ArcGIS Pro | Documentation 

[StevenSchwartz1]

It is not my intention to use geodesic computations. I would like to know if/when using the Calculate Field or Calculate Geometry for area computations, are they using planar or geodesic methods? Is it set by the data frame or geodatabase source?

[DanPatterson]

if everything is in a projected coordinate system, then that would be the default.

although I have learned that explicit is better than implicit

[StevenSchwartz1]

Thank you - can you give me an opinion on the area calculations...which is more accurate? Calculate Field which I divide the shape area by 43560 for acreage, or Calculate Geometry using the area property drop down, acres unit. I am getting a slight difference for all of my computations.