Hey Muhammad H.
It depends a bit if it's a self-hosted site or it's in your clients account.
If it's in you clients Webflow workspace there is really only changes they have to worry about. Generally I do not recommend clients to make changes outside the CMS. You'll be undoing a lot of their work.
But typical is that you allow an average labour time on a monthly basis as a retainer. Inclusions are backups, security, updates, utilised 3rd party plugins, changes within existing content structure.
Price guide would be:
Hosting only is usually at $85+GST (I'm in Australia)
Hosting and Content updates $285 + GST
If you include landing pages or other stuff then this grows pretty quickly. (e.g. the above + 1 landing page per quarter $900 + GST)
I like hosting the clients side in my own workspace so I can charge the monthly retainer myself.
I use ClickUp for everything. But the software doesn't matter, the client experience does.