You can do almost exactly this with keyword bookmarks. The only change is that you need to put the “keyword” at the start of the URL. So @l linux rather than linux @l.
Create a new bookmark with these settings:
Name: Whatever you want.
URL: The search query you want with the text replaced by %s. For example https://kagi.com/search?q=%s+site:https://lemm.ee.
Keyword: The tag you want. Such as @l.
Now you can type @l foobar in the URL bar and it will go to https://kagi.com/search?q=foobar+site:https://lemm.ee. (Or whatever search engine you have configured.
Keywords can also be used for non-search bookmarks and javascript bookmarklets which are very convenient.