DDEV-Local depends on the deb.sury.org Debian packages for PHP, so will follow those as the changes are made. Currently deb.sury.org packages PHP8.0 with xdebug 3.0, but it's not hard to get xdebug 3.0 with earlier PHP versions until that changes.
You can compile and install xdebug 3.0 for PHP7.3 or 7.4. Place this file as .ddev/web-build/Dockerfile in your project's .ddev directory:
ARG BASE_IMAGE FROM $BASE_IMAGE RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y -o Dpkg::Options::="--force-confold" --no-install-recommends --no-install-suggests php-dev php-pear build-essential