Can I change my terminal environment to bash shell using a script and then execute other commands after changing the shell in the same script?

I am trying to write a script that sets my main terminal to use bash shell. I know the #!/bin/bash will call all the commands in the script to be run with the bash shell but what I want is a script that specifically that changes the shell of my terminal to bash.

for example: (this is how my terminal looks like when it is opened.)

$

when i want to set the terminal to bash I manually type the bash command and press enter.

$bash

outcome:

[tyg@rooto ~]$

The problem is if I write a script using the above command it works but any command after the bash command in the script fails to execute.
for example

#!/bin/bash
bash
echo "setting terminal environment to bash"
echo "success"

output:

[tyg@rooto ~]$ 

Expected output: (something like this)

[tyg@rooto ~]$ setting terminal environment to bash
[tyg@rooto ~]$ success

or (Like this)

[tyg@rooto ~]$
[tyg@rooto ~]$ setting environment
[tyg@rooto ~]$ success

any of the above is what I assume should be expected. Why are the two echo commands in the script failing to execute and is there a fix to this. Thanks