There are a few numbers of crypto wallets today, from Trust wallet to Math wallet and atomic but I want to ask why some wallets have 12 words recovery seed and some have 14 and more?
Also is higher the number the better with security? I read somewhere that if you can get 6 out of 12 recovery seed you may be able to get the rest, is this true? I just want to know how far wallet security can go.
So as you have been already told that the standard practice for wallet using the BIP-39 standard the seed phrases are 12 words or 24 mnemonic entropy and it's secure.The word list contains total 2048 words from which they are derived by the wallets but if you say about extra security then you can use passphrase along with your 12 or 24 word seed phrase but remember to safely store both of them on offline storage as without it you cannot access your funds.
Now if you say that you know only 6 words out of 12 then I would say it's near to impossible brute force and crack the rest of words because there are lot of possible combinations as you are missing 6 words out of it.See this
answer where only one word is missing and we have so many possibilities so you are wrong on this part I would say.
About brute forcing seed phrase. On a computer, 4 words can be brute forced in some minutes, while 5 words can be brute forced in some hours. 6 words shouldn't take more than 2 or more days. I have not practically tested this before though. As long as an attacker has the remaining words correctly and not scattered or disarranged, brute forcing it is possible.
This is why the standard practice is 12 words long with full security and really hard to brute force that will take some years to crack it and the small word can easily be brute forced out of the list of 2048 but still there are lot of combinations to them.