Yes, you can dynamically derive pdas in the list of extra_accounts_meta! Here is an example Anchor program you can reference.

If the pda seeds are addresses of other accounts, you reference them by index.

For example, these lines here:

// index 0-3 are the accounts required for token transfer (source, mint, destination, owner)
// index 4 is address of ExtraAccountMetaList account
let account_metas = vec![
    // index 5, wrapped SOL mint
    ExtraAccountMeta::new_with_pubkey(&ctx.accounts.wsol_mint.key(), false, false)?,
    // index 6, token program
    ExtraAccountMeta::new_with_pubkey(&ctx.accounts.token_program.key(), false, false)?,
    // index 7, associated token program
    ExtraAccountMeta::new_with_pubkey(
        &ctx.accounts.associated_token_program.key(),
        false,
        false,
    )?,
    // index 8, delegate PDA
    ExtraAccountMeta::new_with_seeds(
        &[Seed::Literal {
            bytes: "delegate".as_bytes().to_vec(),
        }],
        false, // is_signer
        false,  // is_writable
    )?,
    // index 9, delegate wrapped SOL token account
    ExtraAccountMeta::new_external_pda_with_seeds(
        7, // associated token program index
        &[
            Seed::AccountKey { index: 8 }, // owner index (delegate PDA)
            Seed::AccountKey { index: 6 }, // token program index
            Seed::AccountKey { index: 5 }, // wsol mint index
        ],
        false, // is_signer
        true,  // is_writable
    )?,
    // index 10, sender wrapped SOL token account
    ExtraAccountMeta::new_external_pda_with_seeds(
        7, // associated token program index
        &[
            Seed::AccountKey { index: 3 }, // owner index
            Seed::AccountKey { index: 6 }, // token program index
            Seed::AccountKey { index: 5 }, // wsol mint index
        ],
        false, // is_signer
        true,  // is_writable
    )?,
];