Yes, it is. To increase request size in Apache, add directive LimitRequestFieldSize to the configuration file. Default value is 8190 bytes. To increase it 2 times add
LimitRequestFieldSize 16380. Don't know if it will work from .htaccess. Probably not, so this is the question to support team, but.... I'd strongly suggest you not adding as much data to the cookies as your web-site clients might experience a whole lot of other problems with large cookies. Why don't simply save some pseudo-random hash to clients machine and all the data in your DB? This is also has better security than cookies.