Where do I find the Base Link URL/Secure Base Link URL in the database (not the Base URL or Secure Base URL)
By default, Base Link URL value getting from Base Url. So if you find base_link_url in core_config_data table, you cant find those value.
If you change base link url value in Stores -> Configuration -> Base Link Url at those time, core_config_data table in database generate one new entry for those.
If you uncheck Use system value after textbox of Base link url and save at that time, core_config_data table in database generate one new entry for value of textfield of Link url.
Same process happened for unsecure url.
If Both value are changed in Configuration,
Two new entry are generate in core_config_data table.
if issue solved, Click Kudo/Accept as solutions.