The dimensional accuracy is important if you want to build parts, which have to fit together precisely. Shrinking of the polymer plays also an important role at this part. To handle this issue, you can set the extrusion multiplier or the extrusion width for a perfect result. Also, the first layer height or a constant dimensional error of the printer could be a problem.
Adjust first layer height
For dimensional accuracy it is necessary to set the first layer correctly. Figure it out by changing in small steps. If it is set lower than the first layer should be, too much plastic will come out of the nozzle and this error will continue to the next 10-20 layers. The result will be oversized layers.
For dimensional accuracy the amount of extruded material is a limiting factor for success. Start at an extrusion multiplier from 1, and if too much plastic will be extruded, decease it in 5% steps. It depends on which material you use, which printer and on the nozzle diameter, how easy the material flows.
Change extrusion width
A correct extrusion width is necessary for dimensional accuracy. If the extrusion is set too wide or too small, the whole part becomes lager or thinner than wanted. To avoid this issue, try to set the extrusion width just as the nozzle diameter.
To minimize the shrinking effect of a polymer, scale the part a little bigger. Previously, a part should be printed and measured.
Horizontal size compensation
This option can be used, if the offset of the X and Y axis are not sized precisely. The accuracy can be tested with printed parts, which must be measured in X and Y dimensions. After adapting the slicer settings.