m0useanswered grow question 5 months ago They look healthy and I don't think you need to transplant them. They will be root bound "ring roots" but that's normal in pots. Its a good size over all for them.
If you where going to up size them though, its best to go with a size that's double or triple its current pot.
Eg. 1L 2-3L |OR| 10L 20-30L pot.
They will need liquid feeds as top dressing a pot with amendments that's root bound is hard. Does not always work out well so liquid nutrition gets in all the spots that are needed to feed the plant. Also love using a wetting agent to help break surface tension like Yucca.
Good Luck!