There isn't anything more you can do to increase your selling limits, as you list and sell more items it will keep increasing.
Be aware that whilst private sellers don't pay tax on selling off their own personal items, HMRC may send you a nudge letter asking you to confirm that you are a private seller, only because many items in your collection are new and same category, which will likely be a trigger.
eBay will pass on data to HMRC automatically if you're selling 30 or more items a year OR have total earnings over the equivalent of £1,740. eBay will automatically share this information with HMRC by 31 January 2025 – the first lot of data-sharing will cover the 2023/24 tax year.