You have to use it and pay back later. You will be offered higher limit after 3-6 months.
Credit score is just a number. All lenders want to see how you use your credit cards. If you just opened them and never used this is not a good sign for them
Just as an example of how meaningless credit scores are, I recently almost maxed out my HSBC Premier card due to taking advantage of a 0% purchase offer. My credit scores are still “excellent” yet, when I look at my credit card offers in Credit Karma, ClearScore and Experian, there is only one credit builder card. It says that I’m ineligible for all others.
It’s clear why - I’ve pretty much maxed out one of my cards. I still have over £30K of credit available on my other cards so I don’t need or want another card, so I’m not at all bothered. I’ll be below 50% usage on that card in a couple of months, anyway, because HSBC are raising the credit limit (without me asking) and, of course, I’m paying off the purchase every month, too.