Q: transferring data from backup to new mac

If you use Migration Assistant (in the Utilities folder), you should be able to select categories to transfer or ignore.

If you're referring to selection within categories in Migration Assistant, there's a limit to how selective you can be for file transfer. With files like photos and fami videos, which can take a lot of space, it's best to keep them archived separate from your internal boot drive, especially if it's a relatively small SSD.

Is this a Time Machine backup or something else

Then you have to either install OSX on a bigger disk or migrate less data to the existing disk

Move your content to a new Mac - Apple Support

You will need a disk big enough to restore the backup to.