What's the best combo of paint & varnish for outdoor sculptures?

This will be better to use instead of the polyurethane Paint

For the strongest protection against the elements, use paint on your wooden outdoor furniture. Although you will be losing the original look of the wood, the protection will be worth it. Paint will reflect the UV radiation from the sun and actually protect the wood underneath instead of causing it problems with rot. Latex paint will work better in this situation than oil-based paints because it will last longer and you should find it easier to apply. Depending on your furniture and the weather it deals with, you should reapply the paint every so often when you notice fading, chipping, or peeling. Add Water Sealers

If you live in an area that receives a lot of rain, or even if you just want to keep your wooden outdoor furniture completely protected, you should look into applying a water sealant. This will keep the beautiful look of your wood while also giving it the protection it needs. The nice thing about a water sealer is that it not only protects your furniture from moisture outside, but it will also allow damp wood within the sealant to dry faster in order to avoid splitting, rotting, and warping.Water repellent preservatives may also be used as a treatment for bare wood before priming and painting or in areas where old paint has peeled, exposing bare wood. This treatment keeps rain or dew from penetrating into the wood, especially at joints and end grain, and thus decreases the shrinking and swelling of wood. As a result, less stress is placed on the paint film, and its service life is extended. This stability is achieved by the small amount of wax present in water-repellent preservatives. The fungicide inhibits surface decay. Use a MARINE water sealant for boats ships maybe someone else will offer more help