Configuration

from pydantic import BaseModel, ConfigDict, ValidationError


class Model(BaseModel):
    model_config = ConfigDict(str_max_length=10)

    v: str

Change behaviour globally

from pydantic import BaseModel, ConfigDict


class Parent(BaseModel):
    model_config = ConfigDict(extra='allow')


class Model(Parent):
    model_config = ConfigDict(str_to_lower=True)  # (1)!

    x: str