I just brought a 8 month old puppie jack russell cross king charles spanial I bought all the food and dried which the owner told me got him home and all he tends to eat is bonio biscuits and chews nothing else please could someone help me I am abit worried about this but he drinks

Jack Russell and King Charles, I'm trying to picture that, I bet he is adorable.
How long has he been in his new home? If he is acting fine otherwise, no vomiting/diarrhea, is active and happy I wouldn't worry so much if it only continues for a couple days.
If he is drinking well and eating HIS treats and not yours he should be fine, he is settling in.
Stay away from free feeding, put his food down give him ample opportunity to eat and then take it up, do this a two to three times a day.
When he gets the idea of when his meal is served he should be willing to eat.
If he continues to not eat call your vet just to be safe.

I do have to ask. How many treats is he getting every day? Maybe he's getting too many treats, and isn't hungry enough to eat his regular dog food.

Try cutting back on the treats.

I do have to ask. How many treats is he getting every day? Maybe he's getting too many treats, and isn't hungry enough to eat his regular dog food.

Try cutting back on the treats.

Yes, great thought. If I do say so myself.

Sorry, had to spread the rep.