Tummy time
Tummy time is important exercise for babies and can be started from birth. Newborn babies need tummy time to strengthen the head and neck muscles. It also prevents flat head or plagiocephaly. The bones of the head are still soft and the back of the head will become flat if the baby is not moved or given tummy time.
Simply put them on their tummy 3 times a day for 10-15 minutes. You can use a play mat, the changing mat, your lap, over your shoulder or on a fit ball. Look at their face and try to get them to push up on their arms to look at you. They also like to look in a mirror at themselves! If they already have a flat spot roll them onto the other side. Put a roll of towel under them or simply turn them.
Tummy Time https://www.pregnancybirthbaby.org.au/tummy-time
Bonding
This is a great time to bond with your baby, lots of cuddles, be very responsive to their cry. They will learn to trust that you are responsive to their needs. Mutual gaze and affection is so important. Some babies start smiling as early as 2 weeks but most will smile at 6 weeks.
If you find this difficult try some baby massage or put the baby in a carry sling. Their brain is developing, and they are creating bonds of trust with you already. You cannot spoil a baby too much in these early weeks, do not let anyone tell you to put the baby down. You are not creating a problem for yourself by picking them up and feeding them on demand. Babies do not have demanding or manipulative behaviors. They have considerably basic needs and you are their world.
Importance of bonding: https://kidshealth.org/en/parents/bonding.html