Will I lose any data if I change my Apple Account email?

Let’s consider what “change the ID” might mean. There are two distinct possibilities. I suspect you mean the second of these.

1. Change the email address associated with your Apple Account (formerly called Apple ID). Here is how to do that: Change your Apple Account primary email address - Apple Support. If you do this, your Apple Account address will change on every Apple device you own.
2. Use a different Apple Account on the newer Mac. This is basically saying a different person is using the second Mac. That person does not own any of the data the first person owned. In fact, before doing this, the newer Mac should be thoroughly cleansed as follows: What to do before you sell, give away, trade in, or recycle your Mac - Apple Support. You may then establish Family Sharing if you wish after the new Apple Account address”moves in” to this Mac.

Also note each person, regardless of age, should have her/his own, unique Apple Account.

Make sure that each family member has a unique Apple Account - Apple Support