If you are upgrading from 2.2.8 to 2.3.3 would it be advisable to start a fresh eg
composer create-project --repository-url=https://repo.magento.com/ magento/project-community-edition myproject
and copy over any customisations (design, composer installs etc)
or is it best to go through the normal upgrade process eg
echo "Deleting vendor..."
rm -rf vendor
rm -rf var/cache/*
rm -rf var/page_cache/*
rm -rf var/generation/*
echo "Insert upgraded magento version"
composer require magento/product-community-edition 2.3.3 --no-update
echo "Installing new packages"
composer update