It depends what you want to protect the figure from. If you are trying to protect it from UV discolouration (e.g. yellowing), you can try this UV protection spray from Michaels:
https://canada.michaels.com/en/krylo.../10173870.html
For me, I installed a UV protection film on the glass case where I'm displaying the figures.
Somebody on the board installed the UV protection film on the windows in his display room.