I am attaching an article "Getting Started in Control Line Fun Scale". The Fun Scale event (AMA event 526) is probably the easiest way to start flying scale again, and converting an RC ARF is pretty straightfoward. There are many choices from various manufacturers, so pick your favorite. It is great to have retracts, flaps, etc. all built in the ARF. And since Fun Scale scoring is heavily weighted towards flying (versus static scoring), an ARF that is flown well is very competitive in contests if you want to compete. Pete's Bearcat in the article won 1st place (Fun Scale) at the 2024 AMA National Championships.
Going beyond Fun Scale into other scale events (Sport Scale, Profile Scale, Authentic Scale, 1/2A Scale, FAI F4B Scale) takes more thought and consideration as the other commenters noted. If you are interested in these other events, the starting point is to read the rules thoroughly.
Looking forward to seeing what you build at the 2025 AMA Nationals in Muncie (July 2025).