I think that what you give as an allowance needs to work for your family. And reflect your values, your financial situation, your child's understanding and whether your child needs any money - if they get everything they need from you anyway, then it's not necessary to give an allowance. But giving an allowance does give you an opportunity to teach money management, which is a vital skill.
We consider that the kids' main job is school. As it gets harder the higher they go, they get more money when they go up a year. We also use the allowance to teach about finance, starting with saving vs spending.
Ours started at £1 per week in Primary 1, rising by a pound each year.
We take half of that and put it into longterm savings for the kids, to which we also contribute separately. (Very longterm, like for a first car or college after school.)
As with DC 1 and 2, when DC3 is 16, we will move on to budgeting. This means a weekly allowance for everything, clothes, bus travel, fun, dinner money, hair cuts etc. That way we'll practice saving and managing money for independent living together, while we are available to spot any issues as they arise and can help and explain how to solve them.
DC1 fell off the wagon in the first year at uni, but then used all the budgeting skills we had practiced by second year.
DC2 is back home thanks to lockdown, so no idea whether the budgeting skills are there or not.
And DC3 at 14 now receives £4.50 per week. Spends nothing, even saves up the school dinner money by making a home lunch once or twice a week. As that's a kid with a keen interest in finance, we're even thinking about opening a Junior Stocks and Shares ISA in the near future.
HTH