Do I need to convert varchar(32) and varcha(64) to update from MySQL 5.7 to 8.0
No you can change the character set, because you don't come to the limit that is explained in the article.

The InnoDB storage engine has a maximum index length of 767 bytes, so for utf8 or utf8mb4 columns, you can index a maximum of 255 or 191 character.

So if your utf8 column varchar has a size of more than 191 characters, you will get an error when converting, because tf8mb4 needs 4 bytes per characters and that will exceed the limit.
But as you only have 32 and 64 characters you are wide blow the limit of 191