CPUs are designed to a type of socket. Yours for example is 1151. It was followed by 1151v2 and then 1200, 1700 and now 1851. Each of those are only compatible with chips released for that socket. In the time that Intel went through 4 of those socket types amd just had one socket type, am4. If you had an am4 board you'd have a pretty easy time updating your bios to support the new chips. Unfortunately you won't have such luck on an older Intel platform.

If you don't have a 7700k there is always the potential to upgrade to it. The problem is the price. Unless someone is giving you the upgrade for free, it's unlikely to be worth whatever you're going to spend on it. whatever chip you have is on the same generation and will still have similar limitations of being an older design.

If you want to do as cheap if an upgrade as possible, you do have some options. Since you have ddr4 memory you can still bring that forward to a new cpu/mobo combo if you don't buy something completely modern. For example a 5600x and an am4 board would be a huge uplift. There are also good deals toxbe found on 12-14 gen Intel chips with a ddr4 board. Keep in mind both of these suggestions will also have no upgrade path as they have both already been phased out. But that's the trade off for keeping cost down.