user15490: A transaction can be RBF if itself is a RBF, or it spends outputs from a RBF transaction.
Is there a way to use bitcoin RPC node to check if a transaction is spending outputs from a RBF transaction?

user7272: The getrawmempool RPC command, in verbose mode, produces an output that contains all known mempool transactions for your nodes. This output contains a bip125-replaceable boolean field which you can use to determine if a tx is explicitly or implicitly replaceable by fee.

user103097: Based on Raghav Sood's answer, I found the more specific answer to the OP would be using getmempoolentry, in order to get an individual transaction info. Otherwise you'll be flooded with tons of transactions. Documented here
You can also use gettransaction, it returns bip125-replaceable flag as well, however just for Bitcore prior to 0.10.0 according to this

15490: <p>A transaction can be RBF if itself is a RBF, or it spends outputs from a RBF transaction.</p>
<p>Is there a way to use bitcoin RPC node to check if a transaction is spending outputs from a RBF transaction?</p>
 7272: <p>The <code>getrawmempool</code> RPC command, in verbose mode, produces an output that contains all known mempool transactions for your nodes. This output contains a <code>bip125-replaceable</code> boolean field which you can use to determine if a tx is explicitly or implicitly replaceable by fee.</p>
 103097: <p>Based on Raghav Sood's answer, I found the more specific answer to the OP would be using <code>getmempoolentry</code>, in order to get an individual transaction info. Otherwise you'll be flooded with tons of transactions. Documented <a href="https://chainquery.com/bitcoin-cli/getmempoolentry" rel="nofollow noreferrer">here</a></p>

<p>You can also use <code>gettransaction</code>, it returns <code>bip125-replaceable</code> flag as well, however just for Bitcore prior to 0.10.0 according to <a href="https://chainquery.com/bitcoin-cli/gettransaction" rel="nofollow noreferrer">this</a></p>
