Creating buttons and direct links in custom templates

Hello community, I have an idea not great not like the good of you :), but you can help, I’m creating buttons and direct links in custom templates when they are sent in emails or in hml5, when you have to approve or reject and download budgets , pay or download invoices, well what I need is that you can add in those links {{{*****}}} which is the automatic address that should be placed for such a case.

for the best understanding and to quote an example I worked with:
placing the link to the website and this link appears in the mail I managed to do it with: href = "{{{user_web}}}"
if good is true href = “{{{invoice_guest_url}}}” takes us to the url of the invoice, however the idea is that it becomes independent and leaves the link directly to pay or to download the same invoice as the case may be.

Thank you very much.