The Archives, Categories, and Latest Comments blocks both have float alignment options. For some reason, however, the Latest Posts block does not have float alignment options. Since all the other blocks based on legacy widgets have float alignment options, I think the Latest Posts block should have them as well.

Related issues and PRs

• Latest Posts block: use align supports flag + add left/right align support #10707 would fix this issue
• related issue for Categories block: Categories block: add wide alignment support #11415
• related issue for Archives block: Archives block: add wide and full alignment support #11416