How can you determine the default length of an HMAC openssl digest?

I need to find the number of bits (and/or hex digits) generated by an openssl HMAC digest. I generated the following function which can be included with source command, but I could not tease out a simpler method from the openssl man pages.

#!/bin/bash
# The following wrapper assumes that this is included in a "source"
# statement and needs guarding against possible multiple includes due
# to nesting
if [[ -z "${__hmacsslmacbits}" ]] ; then
    export __hmacsslmacbits=1

    function sslmacbits()
        # sslmacbits dgst
    {
        ########################################################
        # A constant to convert number of digest hex characters
        # to the number of bits generated by a digest.
        ########################################################
        local CHEXBITS=4

        ########################################################
        # The name of the digest as arg #1.
        ########################################################
        local dgstname

        ########################################################
        # The digest generated from openssl and the hex string
        # extracted from that.
        ########################################################
        local digest
        local digesthex
        
        ########################################################
        # Use the installed copy of openssl to verify the
        # information start by verifying openssl is installed
        ########################################################
        which openssl > /dev/null
        if [[ ! $? ]]; then
            echo "Privileged retrival of openssl" >&2
            sudo apt-get install openssl
        fi
        if [[ ! $# == 1 ]]; then
            echo "${FUNCTION} missing digest name" >&2
            exit 1
        fi
        dgstname=$1
    
        ########################################################
        # Verify that the requested digest exists in the
        # installed copy of openssl.
        ########################################################
        openssl list -digest-commands\
            |grep ${dgstname} > /dev/null
        if [[ ! $? ]]; then
            echo "${FUNCTION} ${dgstname} not installed " \
                "in openssl" >&2
            exit 2
        fi
    
        ########################################################
        # Make sure that openssl generates the strongest
        # digest for the shake digests (see -xoflen):
    # https://www.openssl.org/docs/man3.0/man1/openssl-dgst.html
        ########################################################
        chkopenssl="openssl ${dgstname} -hex"
        case ${dgstname} in 
            shake128)
                chkopenssl="${chkopenssl} -xoflen 32"
                ;;
            shake256)
                chkopenssl="${chkopenssl} -xoflen 64"
                ;;
        esac
    
        ########################################################
        # Now we have the correct invocation of openssl for
        # each digest invoke the digest on "Hello World"
        # string and get the result
        ########################################################
        digest=$(${chkopenssl} <<<"Hello World")
    
        ########################################################
        # The resulting string in digest contains a string with
        # the uppercase name of the digest, the file name
        # (in this case stdin) in  parentheses, followed by
        # an "= " string and then the hex digits that compose
        # the digest.  E.G.
        # SHA256(/etc/hosts)= 878ab7da...cb0f648b
        # So we use a nice pattern match to strip off the
        # unwanted characters at the front.
        digesthex=${digest##*= }
    
        ########################################################
        # Now we count the number of hex generated digits and
        # convert that to the number of bits generated
        ########################################################
        echo "$((${#digesthex} / ${CHEXBITS}))"
    }
    export -f sslmacbits
fi # if [[ -z "${__hmacsslmacbits}" ]]

I had hoped that something related to the property of openssl commands would yield the result, but the man page was sufficiently opaque that I could not find a path to the solution.

With my above script, I generate:

echo $(sslmacbits sha1)

and get

10 Hopefully there is a better method?