Hi GBarkin,
When opening an activity record, a modal dialog of form will pou up.
Would this feature be what you expect?

If so, currently there is no similar OOB setting for us to apply such behavior to other entities.
In other word, it's a very new feature from 2020 wave 1 release, and only activity entities are supported at present.
However, we could still achieve it with some customization.
1. Download latest Ribbon Workbench and import it in your environment.
2. Create a solution which contains an entity which you would like to add customization, and select one view.
3. Copy an existing button, e.g: Add to marketing list, because this button will only display when only one record is selected.
Then change properties of the copied.

4. Create an Enable Rule:
only display custom button when only one entity record is selected.

create a simple Display Rule:

create a custom javascript action command, pass "SelectedControlSelectedItemIds" parameter to our custom function,
this parameter stands for GUID of selected record;
then apply two rules for the command.

5. function code:
function openDialog(selectedRecord) {
var pageInput = {
pageType: "entityrecord",
entityName: "account",
formType: 2,
entityId: selectedRecord[0]
};
var navigationOptions = {
target: 2,
width: { value: 80, unit: "%" },
position: 1
};
Xrm.Navigation.navigateTo(pageInput, navigationOptions);
console.log(selectedRecord);
}
Xrm.Navigation.navigateTo is a new client API which could open a record in dialog.
Result:
When I selected an account record, the button will appear:

A dialog will open for selected record.
In addition, there are other methods to open a record:
1. we could also right click a record and "Open link in new tab" to view record in a new tab, while list view will keep open.

2. When we opened a record form, click caret at upper left corner,
it will display all rows of current entitylist page in a panel.
e.g: In All Accounts view, there are 3 pages record, open a record in page 2.

All rows in page 2 will display in left panel, we can move throught selected record without leave.

Finally, you could submit your requirement to Ideas forum.
Regards,
Clofly