Every capable module's Workflows tab, at both organisation and project level.
The Workflows tab
Workflow templates are not kept in one central admin screen. They live in each tool's own settings, on a Workflows tab: claim workflows on the Contracts settings page, submittal workflows on the Submittals page, and so on. The reasoning is that the people who own a tool own its process.
Two levels
Open one of those tabs and you see two lists. The project's own templates, and below them a card holding your organisation's templates. Organisation templates are the company standard; project templates are what actually runs on this job. Activating an organisation template here creates a project copy.
Host only
These pages sit under Tools, which only host organisation members with the right permissions can open. Guests are frequently inside workflows as approvers, and act from the record and from My Items, but the templates and the bindings stay host side.
Which tools have one
Most modules that have a submitted state have a workflow: contracts and their claims and variations, procurement recommendations and contract execution, submittals, site diaries, bookings, timesheets, incidents, inductions, permits and method statements. If a tool has an approval, it has a template behind it.