So what do you want? Non-repeated but freezing at last frame?
setPedAnimation(thePlayer, "sunbathe", "parksit_w_in", -1, false, false, false, false)
-- ^^^^^ loop ^^^^^ freeze at last frame
-- this one will not loop and will freeze at last frame:
setPedAnimation(thePlayer, "sunbathe", "parksit_w_in", -1, false, false, false, true)