The pool of available IPv4 resources is nearly completely exhausted and RIRs can no longer satisfy all requests for additional IPv4 addresses. RIRs have already implemented stricter criteria, which means that you will need to provide strong justification for any IPv4 requests and still should expect to receive smaller allocations than in the past.
Another method of acquiring additional IP addresses is to purchase them from another entity that is not utilizing these resources. Some RIRs, like ARIN, provide services that facilitate the transfer of IPv4 resources. Bear in mind that this can be expensive.
Consider maximizing your existing address pool first with an IPAM solution. It will reduce the need for additional addresses, and help with your request to the RIR.