There are screentone brushes,
Also you can make your screentone as @Grum999 link, [you can use a gray tone palette for that]
you can also download some screentone texture.
Here is a link to a previous person asking for screen tone brushes;
Krita also have a couple default manga style brushes [ sparkles, bokeh, heart shapes]
I’ll add a couple more tools.
Here is Rogudator’s Speech Bubble Generator;
My speech bubble set;
for inking pens good ones can be found in Krita-artists brush section . I suggest rakurris, schordinger cat’s, concept and illustration [illustration set] , lilly mist set [for the manga effects]
Here is a another helpful vector set [can be useful for additional toning]
If you are going to do the halftoning effect you can use my gray tone palette;
Edit: I added LillyMist brushes in the suggestion.
