It is well known that FDM printed parts have slight dimensional errors, such as undersized holes. The Horizontal Expansion setting In Cura -usually hidden within Shell menu- allows for set a compensation value when fitting pieces. Values between -0.05 and -0.2 mm (for a 0.4 noodle) usually give good results.

Here is a simple and convenient test that can be done without a caliper. This piece was designed to determine which value gives the right fit. You only need a set of Allen keys-metric (hex keys) of 2, 4, 6 and/or 8 mm. This is a small piece of 25 x 20 x 10 mm, so you can print a set of them using different Horizontal Expansion values.