Change apple ID

If it's the same account yes, changing an account (assuming you mean change the primary email address on it) will affect everywhere you use it : Change your Apple ID - Apple Support

Or do you mean logging out of the account on the iPhone and logging into a different account ? If you do it will depend upon where you log out and in, and what you have enabled e.g. Photo Stream

There may be some data loss, but you can minimize it. If syncing photos with iCloud, ensure Optimization is turned off in Settings/Your Name/iCloud/Photos and/or in Photos/Preferences/iCloud. Then make sure full resolution photos are on the device/computer. When signing out of iCloud, if asked whether you want to retain data, choose yes. Messages conversations will be lost if they are addressed to the ID. See the article below for other places that the old ID should be removed. See Winston Churchill's response in the below discussion. Also set up Family Sharing to keep access to your apps/purchases. 

Apple ID – Create

How to transfer all files from one iCloud account to another

 Apple ID email address or password - What to do after you change

You can try setting up Family Sharing between the 2 IDs if you want to be able to share purchases made with the IDs.

Family Sharing

Family Sharing - Set up