I know that various sources say that red junglefowl chicks consume mostly--if not almost exclusively--animal matter, and I just read a very interesting study by Savory et al. 1978 which observed that feral chicks would consume about 65% invertebrates for their first month of life.
I've read this too, in a more recent publication. It even applies to bird species where the adult diet is essentially vegetarian; the adults catch insects to feed to their chicks in the nest. Many altricial chicks have an entirely insectivore diet, irrespective of the typical adult diet for that species. I'll try to find the reference for that (can't remember it offhand).
Should we be throwing chick starter out the window and using game bird feed instead? Or homemade feed supplemented with a ton of fish?
I last used it in May 2020. Every brood since then has eaten homemade feed. The chicks here get (a lot of) extra mealworms.
From hatch live mealworms are offered, and the broody enthusiastically teaches her charges that this is food, above all other offerings. Nothing else I give elicits such a response. The chicks eat them with gusto within a day or so. (They also like sardines, tuna, and other fish, but they don't get offered that on a daily basis. Chickens' natural diet must be terrestrial, given their lack of waterproofing and avoidance of large bodies of water that might contain actual fish.)
The broodies learn early that if they bring their brood to a door when it is quiet (no adult birds around to crash the party) and I spot them (sometimes they spot me through a glass door and hurtle over, with chicks flying in pursuit

) they get offered a tub of live mealworms, and as long as she doesn't screech so loud as to attract everyone else, they will get their fill. The chicks continue to employ the same tactics once they're on their own (in the wilderness teen months). And they wean themselves off in their own time.
Please note that last sentence. My doorways are not permanently under siege by chickens, despite the fact that they all know live mealworms are available on demand - they've known it since birth. Few adults come to ask for some, and only when they need them. Chicks really need them. Juveniles need them sporadically. Adults need them occasionally. Maria comes marching in for them when she's laying, but is not now she is moulting. I'm not sure whether her being 8 has anything to do with it or not (Venka is also 8 and also lays - though not as many as Maria - and she has never come for them).
So I would say yes, offer chicks plenty of animal protein, while they want it. They will self regulate if they know it will be available again and they don't need to hoard. (I would also dump the processed chick feed, but that's an independent issue.)
Here's the latest bunch thriving on them