Kamen Rider Zi-O (2018)

I recommend Den-o to Zio because both of them are Tokusatsu.
but the other reason I Recommend Den-o is because they use Time Travel concept. Also the main characters are Developing from weak to strong.

both are heisei anniversary seasons celebrating their respective decades

both use returning actors

Both are seasons of a Toei tokusatsu franchise: Zenkaiger for Super Sentai and Zi-O for Kamen Rider. They have a heavy focus on being the anniversary of the franchise. Both seasons have a focus on the franchise being part of the bigger world/multiverse. They also have a gimmick that has the power of those seasons stored in them and they also transform into forms that are based on previous seasons' heros.

Both are seasons of a Toei tokusatsu franchise: Gokiager for Super Sentai and Zi-O for Kamen Rider. They have a heavy focus on being the anniversary of the franchise. Both seasons have a focus on the franchise being part of the bigger world/multiverse. Both seasons have many cameos of actors of the previous season of their franchise and both seasons' serve as a way to have continuations of the story for of these seasons. They also have a gimmick that has the power of those seasons stored in them.