Accuracy is a device variable and not an application variable. If you are using a mobile device, the gnss chipset and reciever configuration are the limitations. Newer mobile devices are starting to come out with dual gnss chipsets that can achieve 1 to 3 meter accuracy. 3-5 meter accuracy has been the standard for a while. Otherwise you can pair survey grade GNSS recievers to your device to get better accuracy (Trimble, Eos, Juniper, etc.).
That said, all of that is a non-starter if working inside or anywhere else with poor line of sight to various satellite constellations.
If all of your work is inside then you may want to consider an ArcGIS Indoors solution or if you simply "know" where you are relative to some set of design information you could specify the your location rather than rely on the gps (which you know to be inaccurate indoors).
Poor accuracy is going to be universal to any app in your situation as the accuracy is best in open sky conditions.
- Justin Reynolds, PE
