How to combine ifelse and left_join

I have two data sets. First dataset (AH) has a columns: Account_Number, Account_Name, Market_Value and second data set (AH1) has Account_Number, Market_Value and Fund. I am trying to bring in Fund to the first data set from second dataset for only the Account_Numbers I want. Let's say I want to bring the Funds for the account number that starts with 2 if it does not starts with 2 then I want what it is in Account_Number column. Could you please advise how would I do that? I tried this syntax: ifelse(AH$Account_Number == starts_with("2"),left_join(AH,AH1, by = "Account_Number),AH$Account_Number