can I change Apple ID while still having apps from old one?

You can change your Apple ID for everything but the App Store or as mentioned, set up Family Sharing.

When changing to the new ID, 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.

How to switch Apple IDs on your iPhone or iPad. https://www.imore.com/how-change-apple-id-your-iphone-or-ipad

How to transfer all files from one iCloud account to another. https://discussions.apple.com/thread/7452747

What to do after you change your Apple ID or password - Apple Support. https://support.apple.com/en-us/HT204071

Family Sharing. https://support.apple.com/en-us/HT201060

Family Sharing - Set up. https://support.apple.com/en-us/HT201088

Family Sharing allows sharing, but there’s no means to transfer purchases from one Apple ID to another.

Sharing one Apple ID across multiple folks is not recommended, and usually gets ugly, particularly around messaging, privacy, and purchases.