legal pages give legitimacy to your site, so I'd say you should take the time to set them up. The good news is that some of these pages (privacy policy and ToS, for example) can be generated online and modified with a few clicks to reflect your / your site's / your business' data
For a basic site / blog the minimum number of "legal" pages you'll want to have are:
About / About Me / About Us
Contact
Privacy / Privacy Policy
Terms of Service
Cookies / GDPR (this one you might also replace with just a popup, but I saw some websites having separate pages for Cookies)
If you still have a basic site / blog but on topics that are related to people's or pets' health / wellbeing you also need a Disclaimer page (the Disclaimer page is needed so you can mention that you're not a medic / professional / accredited / whatever health carer and that the info you mention on the site is only tips and / or your unprofessional opinion and that your visitors should consult with a doctor / accredited / official health carer instead of blindly trusting the info they read on your site... unless you are a doctor, of course. In this case you might not need the Disclaimer page)
If you don't know how to formulate your disclaimer you can search for an online Disclaimer generator and use that.
If you have an ecommerce site, on top of the aforementioned pages (minus the Disclaimer one if it's not needed) you might also want to have pages like Refund Policy, Return Policy, Shipping Tracking / Procedures, etc...
Just pull 5-10 big ecommerce sites (Amazon, BestBuy, NewEgg, etc) and check which legal pages they have and try to mimic them if their model applies to your business / site