While there are many options you can consider, you need to choose something that will be practical and will be appreciated by the new parents.
Every baby needs diapers and wipes. They can go through so many of them that the new parents will be so grateful that you chose this as a gift. But there are so many types of baby diapers available on the market that it can be a little difficult to choose one brand or type. When you are choosing wipes, look for brands that are hypoallergenic and made of sustainable materials. This will be good for the environment as well. And you can always ask the parents beforehand if they have a certain brand of diapers in mind. If they are parents for the second time, they will definitely have a good idea of what works.
Otherwise, you can ask any new parent for a recommendation on brands and types that they use. Muslin blankets are great as baby shower gifts because they are so versatile. They can be used as so many different things such as a general blanket, a swaddle, a nursing cover, a burp cloth, a changing pad cover etc. The possibilities are truly endless. You can select a large muslin blanket that can be used for any number of things. These also tend to get softer the more you wash it and they are very breathable. They will have a use in the household even after the baby grows up.
Look into clip-on baby toys that are actually developmental sensory toys. These can simply be clipped onto a car seat or a stroller. It can distract your baby when they get fussy or irritated. And as these don’t have any electronic parts, they can safely be used in public places without disrupting other people. You can purchase a couple of these so that the new parents can attach them to both the car seat and the stroller. Many people tend to gift baby clothes that are sized for newborns. But it is a good idea to select larger-sized baby clothes such as those the baby can wear after about 6 months or even after a year.
Babies tend to outgrow their clothes very fast and they will need large clothing very quickly. And because the parents will definitely be getting newborn sizes as gifts from everyone else, you can choose larger sizes in a mix of sleeve lengths for a bit of versatility. And when you are buying pants, you can choose footed pants as the parents will not need to deal with socks. This means fewer clothing items to remove when changing a diaper. Baby socks will be useful once they are about 12 months when the baby is learning to walk. But as a newborn, socks can be a hindrance and they can get lost very easily.