You can't. The factory finish would be something like a 2-pack catalysing lacquer which requires a spray booth and spray equipment to apply.
Best bet, assuming that they are solid oak, is to scrape off the finish, then sand to P120, and relacquer with something like brushing cellulose lacquers (look for someone like Morrells, a trade supplier, they have depots all over). The problem I can see with any refinishing job is that the current finish appears to be either tinted golden yellow or to have yellowed with age (?). It may be possible to match the colour by giving the oak a coat of golden pine water based stain, diluted to suit, followed by denibbing with a P320 sandpaper once it is dry, before refinishing, however with only one photo on a computer screen which shows considerable colour cast from the lighting/camera (?) it is difficult to say for certain whether this will be needed
The reason for suggesting brushing lacquers is that they can be supplied with an appropriate sheem level to match the existing (possibly in the range 60 to 70%) and being thin they also flow out well from the brush, leaving a smooth surface. Another possibility might be Sadolin, which has a slightly straw tint to it