We are moving from years of SF Classic to LE and I am looking for any kind of guide or documentation on how to build links for customized buttons that include default values, i.e. a new opportunity button on the contact related list that includes a specific record type, a predefined naming convention, the account and contact ID, the StageName .... My old classic buttons open a new opportunity window, but does not include any of the previously defined pre-populated values.

Example of old Classic URL build:

/006/e? 

ent=Opportunity 

&retURL=%2F{!Contact.Id} 

&accid={!Account.Id} 

&RecordType=01230000000iq8S 

&opp3={!Contact.Name} - GRE Donation {!YEAR( TODAY() )} 

&opp9={!TODAY()} 

&opp11=Received

 which ultimately generates the following example URL:

/006/e?ent=Opportunity&retURL=%2F0033000001cfD52&accid=0013000001EJXjn&RecordType=01230000000iq8S&opp3=Lynn+Abruzzo%20-%20GRE%20Donation%202019&opp9=9%2F5%2F2019&opp11=Received

In the New Opportunity page the Name, AccountID, CloseDate, StageName, and RecordID fields are prepopulated witih the above defined values.