Yes, all other Wi-Fi access points and 2.4/5 GHz devices will be considered by the Meraki access points when choosing a channel. Typically leaving the Meraki on automatic (the default setting) will be the ideal setting. Nearby access points on the same channel will typically "share" the air time, nearby access points on overlapping channels will typically create noise and "interfere" with each other, and nearby access points on different channels will not impact each other. If you'd like to avoid interference, you can manually assign channels per AP, or you can configure the Meraki RF Profiles to avoid specific channels.
For example, if you have an access point from another network (Meraki or not Meraki) using channel 36 and very close to your access points, I would recommend using RF Profiles to avoid channel 36.
https://documentation.meraki.com/MR/Radio_Settings/RF_Profiles#Channel_Assignment_Method
If you have a lot of access points overlapping with a lot of access points, a manual channel plan might help.
https://documentation.meraki.com/zGeneral_Administration/Cross-Platform_Content/Radio_Settings/Manua...
Colin Lowenberg
wireless engineer and startup founder, formerly known as "the API guy", now I run a
Furapi, the therapy dog service, and
Lowenberg Labs, an IT consulting company.