Expect something? Yes. Enforce it? Not sure for the first tranche, but make it a prerequisite for continued funding.
One big obstacle is, of course, how to define what to expect from each artist. For example, you can't expect the same level of output from sculptors and musicians. Another big obstacle is obviously the expected quality of output.
I don't pretend to know the solutions to either of those obstacles, but they should be surmountable [1]. I think it's fair to expect some output in exchange for funding, but it doesn't have to be a high expectation.
Personally, I like the idea of hiring artists as full-time with particular projects in mind [2], but intentionally leaving ~50% of their time to personal projects.
[1] Perhaps artist communities themselves could discuss ways to make this exchange work for all parties.
[2] Murals, restorations, beautification of public spaces, etc.
The expectation doesn't have to be too specific or unrealistic. If you agree on some common ground [2], everything else can be fair game for the artist.
Your analogy with the bridge would apply if art also had a minimum viable version. Collapsed to its functional requirements, you could say that visual art is something to look at. But I doubt either party, especially the funding body or the public, would be happy without inserting some quality requirements (i.e., what makes something nice to look at).
Many artists do commissions, so you can see this as a commission with deliberately underspecified requirements.
[1] I won't get into the disagreements between the Pope and Michelangelo, and it's certainly not an example of a good contract, but we can assume that both parties were somewhat satisfied in the end.
[2] For example, both parties need to like it. Or the patron doesn't have to like it, but it needs to appeal to some public audience.
For something like this I think a citizens assembly[1] may work best. Take all artists receiving funding and are NOT up for renewal. Select a number of them randomly to form the assembly. This assembly then reviews submissions from artists up for renewal and determines if they meet a minimum standard for funding to be renewed.
My understanding is that the Irish scheme doesn't force any specific work for the three year period, though I'd expect any artist who takes a three year, ~$60k grant and uses it to do literally nothing may find it hard get a grant in the future, potentially ending their art career. Still, I wouldn't be surprised if a few recipients end up doing that, in which case it's an economic question as to whether the net loss from such freeloaders is more or less than the cost of the bureaucracy necessary to prevent them.
Of course the more fundamental question is whether the whole scheme is even worthwhile. Clearly the Irish government believes that their trial in 2022 demonstrated a positive financial return, but my guess it that it will take decades before we can truly answer this question.