The reason Quickbooks does not let you use Tags for split transactions in Basic and Essentials products is that they want you to upgrade to their more expensive "product".  Tags that allow split transactions are called "Classes" and you have to pay for that premium feature to the tune of $35/month. I used classes for many years on Quickbooks Desktop Pro, but I have lost all previous years classes because I do not want to pay the extra $360 x 2 accounts = $720 a year for the next higher product containing class feature (2022 pricing).

This is no way to treat customers who have been using your software and relied on this feature for their accounts for years. Class functions should be available at all product levels.

As a note, if you need to bulk apply tags:

Banking -> Tags -> See all untagged transactions.

Next tick the transactions to be changed and click 'update tags' to add/remove tags.