This is an area of expertise for me. If it's oil base you can just go over with another oil base. If it's water base you will not be able to go over with oil base. Water base will go over water base but may not last so long so I would recommend a sanding if this is the case for you do not ever use water base stain or paint for fences or decks it's a gimmick. Use oil base stain . If you ask the paint department in homedepot or rona they will always tell you oil base is not for exterior . Reason for this is because they have an intricate product line for water base products that do not last longer than a few years. They tell you to use a pre treatment before painting than if your removing they will try and sell you a removing agent both cost as much as the product itself. A true stain is oil and will never peel as it soaks into the wood where water base peels as it's basically the same thing as paint. cedar naturally does not rot hence it's from rain forests so it does not require being sealed. Oil base does not seal wood and if you use on surfaces that collect water and snow the wood will eventually rot. Water base stain will actually seal the wood but it will peel and degrigate in uv .

IMO a fence that is stained the color of tree trunks is best in order to get it to fade into you landscaping. Pine on your ceiling is guaranteed to mold in Florida. Use a synthetic or aluminum that is finished to look like wood https://www.qualityedge.com/soffit/porch-ceiling/ https://www.qualityedge.com/underdecking-product-details/

Thompson water seal comes in transparent, semi, and solid. They have a gray color. You could lightly pressure wash first. It's easy to do and just reapply when it starts fading. Should last a few years.

A picture would be nice... Keep in mind that what ever colour you choose it will probably show-up lighten than on the samplein daylight once painted.