Of all the years that I've applied for a credit card, I've never seen this (mainly to apply for balance transfers). For example, I was on the barclaycard website to apply for a card, but when I got the card, my starting credit limit was £750, so it was pointless because I was hoping to transfer a balance of £8k. So I didn't use the card and just phoned to close the account.
It definitely does tell you your estimated credit limit. See below.
You would need a 0% spend card not a balance transfer card for this...
But when you do the soft search, it will tell you the chances of acceptance, not your credit limit
I got offered an interim £7200 limit with a near 100% chance of success which was far beyond my expectations. Do the soft credit check on their site and see how you fare. It has NO impact on your actual credit rating.