Most of my clients have kids who left home long ago, so it's not a major concern for me.  Those with kids are smart enough that they will learn from many sources -- including me, if they ask -- that these payments are an advance on what they would otherwise receive next year.  There are some people who are smart enough to have kids but not smart enough to understand taxes, and if those are your clients it is wise to start educating them now.  

TCJA raised taxes for about half my clients, and their attitude was "oh, well."  The new withholding methods with W-4 forms resulted in a lot of people owing more or getting less back than last year.  Their attitude was "oh, well."  For some people, you can explain that their CTC is $3,000 less because of advance payments but $2,000 more because of ARP and by the way their EIC went up by $1,000 also, so the refund is about the same.  They won't really understand what you're trying to explain but will be happy with the usual check nonetheless.