No but I would expect him to make an effort to get to know them and develop a relationship with them.
I honestly don't think blending families work unless you can go all in. That doesn't mean he has to love them but the relationship needs to be able to withstand normal dc irritations and him being able to voice those irritations - like say a dcs job was to wash up but they 'forgot', the step parent would have enough of a good relationship to tell the dc to do it without there being resentment from any of the involved people in that dynamic. That only comes with a good relationship.
So yes not love but he would have to be able to show my dc enough unconditional positive regard (that's not saying he can't get annoyed like a parent would, its a theoretical model of practice).
I have been an unmarried step parent and a married one. It's very hard, the first unmarried step parent relationship worked well dc and step dc wise. Two partners on the same page around values of child rearing, parent actually parented but I was involved, included and we felt much more of a family than what I did as a married step parent because of that.
Some people will say they find disengaging works for them, it didn't work for me. I needed the mum place in the family. Not being their mum, but the mum place if that makes sense. It might sound a bit strange but I did the wife work, the planning days out, films to watch, shared finances so bought his dc (my dcs siblings) clothes when I bought my two, took sdc out when doing trips to the park ect with my friends, I really did see them as my family too. Although I'm not with dcs dad anymore they still come over to see my dc sometimes and they're happy to see me.
With my stb ex husband (roll on April 6th) I was shut out. His son was placed above my dc. It wasn't shared parenting. Some people may like that but I didn't. I didnt want a seperate life and seperate holidays and seperate rules. To me, being a family means being all in. But I do understand others don't feel that way. I wanted my stb x to be all in with my dc. I wanted him to like them as they liked him. He didn't. He was so caught up in his ex drama and his dc drama he couldn't see anything else apart from his dad guilt.